diff --git a/fooof/analysis/error.py b/fooof/analysis/error.py
index 76e8eda5e..ceb85c2d0 100644
--- a/fooof/analysis/error.py
+++ b/fooof/analysis/error.py
@@ -102,7 +102,7 @@ def compute_pointwise_error_fg(fg, plot_errors=True, return_errors=False, **plt_
 
 
 def compute_pointwise_error(model, data):
-    """Calculate pointwise error between original data and a model fit of that data.
+    """Calculate point-wise error between original data and a model fit of that data.
 
     Parameters
     ----------
diff --git a/fooof/bands/bands.py b/fooof/bands/bands.py
index 2a03c6502..6a07a687a 100644
--- a/fooof/bands/bands.py
+++ b/fooof/bands/bands.py
@@ -1,4 +1,4 @@
-"""A data oject for managing band definitions."""
+"""A data object for managing band definitions."""
 
 from collections import OrderedDict
 
@@ -60,7 +60,7 @@ def __len__(self):
         return self.n_bands
 
     def __iter__(self):
-        """Define iteratation as stepping across each band."""
+        """Define iteration as stepping across each band."""
 
         for label, band_definition in self.bands.items():
             yield (label, band_definition)
diff --git a/fooof/core/info.py b/fooof/core/info.py
index dbf344ee6..9cd9c3e49 100644
--- a/fooof/core/info.py
+++ b/fooof/core/info.py
@@ -70,7 +70,7 @@ def get_ap_indices(aperiodic_mode):
     Returns
     -------
     indices : dict
-        Mapping of the column labels and indices for the aperiodc parameters.
+        Mapping of the column labels and indices for the aperiodic parameters.
     """
 
     if aperiodic_mode == 'fixed':
diff --git a/fooof/core/io.py b/fooof/core/io.py
index c135f4933..037238ae1 100644
--- a/fooof/core/io.py
+++ b/fooof/core/io.py
@@ -198,7 +198,7 @@ def load_json(file_name, file_path):
 
 
 def load_jsonlines(file_name, file_path):
-    """Load a jsonlines file, yielding data line by line.
+    """Load a json-lines file, yielding data line by line.
 
     Parameters
     ----------
diff --git a/fooof/core/modutils.py b/fooof/core/modutils.py
index 1027797bb..c342a52c9 100644
--- a/fooof/core/modutils.py
+++ b/fooof/core/modutils.py
@@ -79,7 +79,7 @@ def docs_append_to_section(docstring, section, add):
 
     Parameters
     ----------
-    ds : str
+    docstring : str
         Docstring to update.
     section : str
         Name of the section within the docstring to add to.
diff --git a/fooof/core/reports.py b/fooof/core/reports.py
index a3dc69207..20323b1ce 100644
--- a/fooof/core/reports.py
+++ b/fooof/core/reports.py
@@ -16,6 +16,7 @@
 REPORT_FONT = {'family': 'monospace',
                'weight': 'normal',
                'size': 16}
+SAVE_FORMAT = 'pdf'
 
 ###################################################################################################
 ###################################################################################################
@@ -61,7 +62,7 @@ def save_report_fm(fm, file_name, file_path=None, plt_log=False):
     ax2.set_yticks([])
 
     # Save out the report
-    plt.savefig(fpath(file_path, fname(file_name, 'pdf')))
+    plt.savefig(fpath(file_path, fname(file_name, SAVE_FORMAT)))
     plt.close()
 
 
@@ -104,5 +105,5 @@ def save_report_fg(fg, file_name, file_path=None):
     plot_fg_peak_cens(fg, ax3)
 
     # Save out the report
-    plt.savefig(fpath(file_path, fname(file_name, 'pdf')))
+    plt.savefig(fpath(file_path, fname(file_name, SAVE_FORMAT)))
     plt.close()
diff --git a/fooof/core/utils.py b/fooof/core/utils.py
index 2a224432b..f0fcdb588 100644
--- a/fooof/core/utils.py
+++ b/fooof/core/utils.py
@@ -210,7 +210,7 @@ def check_inds(inds):
     This function works only on indices defined for 1 dimension.
     """
 
-    # Typcasting: if a single int, convert to an array
+    # Typecasting: if a single int, convert to an array
     if isinstance(inds, int):
         inds = np.array([inds])
     # Typecasting: if a list or range, convert to an array
diff --git a/fooof/objs/fit.py b/fooof/objs/fit.py
index e5b007b77..009671b55 100644
--- a/fooof/objs/fit.py
+++ b/fooof/objs/fit.py
@@ -238,14 +238,10 @@ def _reset_internal_settings(self):
             # Bandwidth limits are given in 2-sided peak bandwidth
             #   Convert to gaussian std parameter limits
             self._gauss_std_limits = tuple([bwl / 2 for bwl in self.peak_width_limits])
-            # Bounds for aperiodic fitting. Drops bounds on knee parameter if not set to fit knee
-            self._ap_bounds = self._ap_bounds if self.aperiodic_mode == 'knee' \
-                else tuple(bound[0::2] for bound in self._ap_bounds)
 
         # Otherwise, assume settings are unknown (have been cleared) and set to None
         else:
             self._gauss_std_limits = None
-            self._ap_bounds = None
 
 
     def _reset_data_results(self, clear_freqs=False, clear_spectrum=False, clear_results=False):
@@ -286,7 +282,7 @@ def _reset_data_results(self, clear_freqs=False, clear_spectrum=False, clear_res
             self._peak_fit = None
 
 
-    def add_data(self, freqs, power_spectrum, freq_range=None):
+    def add_data(self, freqs, power_spectrum, freq_range=None, clear_results=True):
         """Add data (frequencies, and power spectrum values) to the current object.
 
         Parameters
@@ -298,6 +294,9 @@ def add_data(self, freqs, power_spectrum, freq_range=None):
         freq_range : list of [float, float], optional
             Frequency range to restrict power spectrum to.
             If not provided, keeps the entire range.
+        clear_results : bool, optional, default: True
+            Whether to clear prior results, if any are present in the object.
+            This should only be set to False if data for the current results are being re-added.
 
         Notes
         -----
@@ -305,10 +304,12 @@ def add_data(self, freqs, power_spectrum, freq_range=None):
         they will be cleared by this method call.
         """
 
-        # If any data is already present, then clear data & results
+        # If any data is already present, then clear previous data
+        # Also clear results, if present, unless indicated not to
         #   This is to ensure object consistency of all data & results
-        if np.any(self.freqs):
-            self._reset_data_results(True, True, True)
+        self._reset_data_results(clear_freqs=self.has_data,
+                                 clear_spectrum=self.has_data,
+                                 clear_results=self.has_model and clear_results)
 
         self.freqs, self.power_spectrum, self.freq_range, self.freq_res = \
             self._prepare_data(freqs, power_spectrum, freq_range, 1, self.verbose)
@@ -717,6 +718,10 @@ def _simple_ap_fit(self, freqs, power_spectrum):
                             np.log10(self.freqs[-1]) - np.log10(self.freqs[0]))
                      if not self._ap_guess[2] else self._ap_guess[2]]
 
+        # Get bounds for aperiodic fitting, dropping knee bound if not set to fit knee
+        ap_bounds = self._ap_bounds if self.aperiodic_mode == 'knee' \
+            else tuple(bound[0::2] for bound in self._ap_bounds)
+
         # Collect together guess parameters
         guess = np.array([off_guess + kne_guess + exp_guess])
 
@@ -729,7 +734,7 @@ def _simple_ap_fit(self, freqs, power_spectrum):
                 warnings.simplefilter("ignore")
                 aperiodic_params, _ = curve_fit(get_ap_func(self.aperiodic_mode),
                                                 freqs, power_spectrum, p0=guess,
-                                                maxfev=self._maxfev, bounds=self._ap_bounds)
+                                                maxfev=self._maxfev, bounds=ap_bounds)
         except RuntimeError:
             raise FitError("Model fitting failed due to not finding parameters in "
                            "the simple aperiodic component fit.")
@@ -774,6 +779,10 @@ def _robust_ap_fit(self, freqs, power_spectrum):
         freqs_ignore = freqs[perc_mask]
         spectrum_ignore = power_spectrum[perc_mask]
 
+        # Get bounds for aperiodic fitting, dropping knee bound if not set to fit knee
+        ap_bounds = self._ap_bounds if self.aperiodic_mode == 'knee' \
+            else tuple(bound[0::2] for bound in self._ap_bounds)
+
         # Second aperiodic fit - using results of first fit as guess parameters
         #  See note in _simple_ap_fit about warnings
         try:
@@ -781,7 +790,7 @@ def _robust_ap_fit(self, freqs, power_spectrum):
                 warnings.simplefilter("ignore")
                 aperiodic_params, _ = curve_fit(get_ap_func(self.aperiodic_mode),
                                                 freqs_ignore, spectrum_ignore, p0=popt,
-                                                maxfev=self._maxfev, bounds=self._ap_bounds)
+                                                maxfev=self._maxfev, bounds=ap_bounds)
         except RuntimeError:
             raise FitError("Model fitting failed due to not finding "
                            "parameters in the robust aperiodic fit.")
@@ -851,7 +860,7 @@ def _fit_peaks(self, flat_iter):
                 guess_std = compute_gauss_std(fwhm)
 
             except ValueError:
-                # This procedure can fail (extremely rarely), if both le & ri ind's end up as None
+                # This procedure can fail (very rarely), if both left & right inds end up as None
                 #   In this case, default the guess to the average of the peak width limits
                 guess_std = np.mean(self.peak_width_limits)
 
@@ -1027,21 +1036,21 @@ def _drop_peak_overlap(self, guess):
         Notes
         -----
         For any gaussians with an overlap that crosses the threshold,
-        the lowest height guess guassian is dropped.
+        the lowest height guess Gaussian is dropped.
         """
 
-        # Sort the peak guesses by increasing frequency, so adjacenent peaks can
-        #   be compared from right to left.
+        # Sort the peak guesses by increasing frequency
+        #   This is so adjacent peaks can be compared from right to left
         guess = sorted(guess, key=lambda x: float(x[0]))
 
         # Calculate standard deviation bounds for checking amount of overlap
-        #   The bounds are the gaussian frequncy +/- gaussian standard deviation
+        #   The bounds are the gaussian frequency +/- gaussian standard deviation
         bounds = [[peak[0] - peak[2] * self._gauss_overlap_thresh,
                    peak[0] + peak[2] * self._gauss_overlap_thresh] for peak in guess]
 
         # Loop through peak bounds, comparing current bound to that of next peak
         #   If the left peak's upper bound extends pass the right peaks lower bound,
-        #   Then drop the guassian with the lower height.
+        #   then drop the Gaussian with the lower height
         drop_inds = []
         for ind, b_0 in enumerate(bounds[:-1]):
             b_1 = bounds[ind + 1]
diff --git a/fooof/objs/group.py b/fooof/objs/group.py
index 8bd293d3a..937563242 100644
--- a/fooof/objs/group.py
+++ b/fooof/objs/group.py
@@ -557,7 +557,7 @@ def _check_width_limits(self):
         """Check and warn about bandwidth limits / frequency resolution interaction."""
 
         # Only check & warn on first power spectrum
-        #   This is to avoid spamming stdout for every spectrum in the group
+        #   This is to avoid spamming standard output for every spectrum in the group
         if self.power_spectra[0, 0] == self.power_spectrum[0]:
             super()._check_width_limits()
 
diff --git a/fooof/objs/utils.py b/fooof/objs/utils.py
index 253a4f13b..65bec0f5b 100644
--- a/fooof/objs/utils.py
+++ b/fooof/objs/utils.py
@@ -138,7 +138,7 @@ def combine_fooofs(fooofs):
     --------
     Combine FOOOF objects together (where `fm1`, `fm2` & `fm3` are assumed to be defined and fit):
 
-    >>> fg = combine_fooofs([fm1, fm2, f3])  # doctest:+SKIP
+    >>> fg = combine_fooofs([fm1, fm2, fm3])  # doctest:+SKIP
 
     Combine FOOOFGroup objects together (where `fg1` & `fg2` are assumed to be defined and fit):
 
diff --git a/fooof/plts/aperiodic.py b/fooof/plts/aperiodic.py
index b20038b81..fafc1dd5e 100644
--- a/fooof/plts/aperiodic.py
+++ b/fooof/plts/aperiodic.py
@@ -70,9 +70,9 @@ def plot_aperiodic_fits(aps, freq_range, control_offset=False,
         Aperiodic parameters. Each row is a parameter set, as [Off, Exp] or [Off, Knee, Exp].
     freq_range : list of [float, float]
         The frequency range to plot the peak fits across, as [f_min, f_max].
-    control_offset : boolean, optonal, default: False
+    control_offset : boolean, optional, default: False
         Whether to control for the offset, by setting it to zero.
-    log_freqs : boolean, optonal, default: False
+    log_freqs : boolean, optional, default: False
         Whether to plot the x-axis in log space.
     colors : str or list of str, optional
         Color(s) to plot data.
diff --git a/fooof/plts/fm.py b/fooof/plts/fm.py
index 6818e4840..68be6ea5b 100644
--- a/fooof/plts/fm.py
+++ b/fooof/plts/fm.py
@@ -283,7 +283,7 @@ def _add_peaks_width(fm, plt_log, ax, **plot_kwargs):
 
     Notes
     -----
-    This line representents the bandwidth (width or gaussian standard deviation) of
+    This line represents the bandwidth (width or gaussian standard deviation) of
     the peak, though what is literally plotted is the full-width half-max.
     """
 
diff --git a/fooof/tests/analysis/test_error.py b/fooof/tests/analysis/test_error.py
index d14307f9f..2a87e1512 100644
--- a/fooof/tests/analysis/test_error.py
+++ b/fooof/tests/analysis/test_error.py
@@ -11,7 +11,7 @@ def test_compute_pointwise_error_fm(tfm):
     assert np.all(errs)
 
 def test_compute_pointwise_error_fm_plt(tfm, skip_if_no_mpl):
-    """Run a seperate test to run with plot pass-through."""
+    """Run a separate test to run with plot pass-through."""
 
     compute_pointwise_error_fm(tfm, True, False)
 
@@ -21,7 +21,7 @@ def test_compute_pointwise_error_fg(tfg):
     assert np.all(errs)
 
 def test_compute_pointwise_error_fg_plt(tfg, skip_if_no_mpl):
-    """Run a seperate test to run with plot pass-through."""
+    """Run a separate test to run with plot pass-through."""
 
     compute_pointwise_error_fg(tfg, True, False)
 
diff --git a/fooof/tests/objs/test_fit.py b/fooof/tests/objs/test_fit.py
index 430b55eed..6a620e893 100644
--- a/fooof/tests/objs/test_fit.py
+++ b/fooof/tests/objs/test_fit.py
@@ -226,36 +226,68 @@ def test_fooof_load():
     for meta_dat in OBJ_DESC['meta_data']:
         assert getattr(tfm, meta_dat) is not None
 
-def test_adds():
-    """Tests methods that add data to FOOOF objects.
+def test_add_data():
+    """Tests method to add data to FOOOF objects."""
 
-    Checks: add_data, add_settings, add_results.
-    """
-
-    # Note: uses it's own tfm, to not add stuff to the global one
+    # This test uses it's own FOOOF object, to not add stuff to the global one
     tfm = get_tfm()
 
-    # Test adding data
+    # Test data for adding
     freqs, pows = np.array([1, 2, 3]), np.array([10, 10, 10])
+
+    # Test adding data
     tfm.add_data(freqs, pows)
+    assert tfm.has_data
     assert np.all(tfm.freqs == freqs)
     assert np.all(tfm.power_spectrum == np.log10(pows))
 
+    # Test that prior data does not get cleared, when requesting not to clear
+    tfm._reset_data_results(True, True, True)
+    tfm.add_results(FOOOFResults([1, 1], [10, 0.5, 0.5], 0.95, 0.02, [10, 0.5, 0.25]))
+    tfm.add_data(freqs, pows, clear_results=False)
+    assert tfm.has_data
+    assert tfm.has_model
+
+    # Test that prior data does get cleared, when requesting not to clear
+    tfm._reset_data_results(True, True, True)
+    tfm.add_data(freqs, pows, clear_results=True)
+    assert tfm.has_data
+    assert not tfm.has_model
+
+def test_add_settings():
+    """Tests method to add settings to FOOOF objects."""
+
+    # This test uses it's own FOOOF object, to not add stuff to the global one
+    tfm = get_tfm()
+
     # Test adding settings
     fooof_settings = FOOOFSettings([1, 4], 6, 0, 2, 'fixed')
     tfm.add_settings(fooof_settings)
     for setting in OBJ_DESC['settings']:
         assert getattr(tfm, setting) == getattr(fooof_settings, setting)
 
+def test_add_meta_data():
+    """Tests method to add meta data to FOOOF objects."""
+
+    # This test uses it's own FOOOF object, to not add stuff to the global one
+    tfm = get_tfm()
+
     # Test adding meta data
     fooof_meta_data = FOOOFMetaData([3, 40], 0.5)
     tfm.add_meta_data(fooof_meta_data)
     for meta_dat in OBJ_DESC['meta_data']:
         assert getattr(tfm, meta_dat) == getattr(fooof_meta_data, meta_dat)
 
+def test_add_results():
+    """Tests method to add results to FOOOF objects."""
+
+    # This test uses it's own FOOOF object, to not add stuff to the global one
+    tfm = get_tfm()
+
     # Test adding results
     fooof_results = FOOOFResults([1, 1], [10, 0.5, 0.5], 0.95, 0.02, [10, 0.5, 0.25])
     tfm.add_results(fooof_results)
+    assert tfm.has_model
     for setting in OBJ_DESC['results']:
         assert getattr(tfm, setting) == getattr(fooof_results, setting.strip('_'))
 
diff --git a/fooof/tests/plts/test_styles.py b/fooof/tests/plts/test_styles.py
index 75b002d1b..f1b2f09af 100644
--- a/fooof/tests/plts/test_styles.py
+++ b/fooof/tests/plts/test_styles.py
@@ -9,7 +9,6 @@ def test_check_n_style(skip_if_no_mpl):
 
     # Check can pass None and do nothing
     check_n_style(None)
-    assert True
 
     # Check can pass a callable
     def checker(*args):
diff --git a/fooof/tests/plts/test_templates.py b/fooof/tests/plts/test_templates.py
index a1e1f3240..f2faa6808 100644
--- a/fooof/tests/plts/test_templates.py
+++ b/fooof/tests/plts/test_templates.py
@@ -12,25 +12,20 @@
 @plot_test
 def test_plot_scatter_1(skip_if_no_mpl):
 
-    dat = np.random.randint(0, 100, 100)
+    data = np.random.randint(0, 100, 100)
 
-    plot_scatter_1(dat, 'label', 'title')
+    plot_scatter_1(data, 'label', 'title')
 
 @plot_test
 def test_plot_scatter_2(skip_if_no_mpl):
 
-    plt.close('all')
+    data1 = np.random.randint(0, 100, 100)
+    data2 = np.random.randint(0, 100, 100)
 
-    dat1 = np.random.randint(0, 100, 100)
-    dat2 = np.random.randint(0, 100, 100)
-
-    plot_scatter_2(dat1, 'label1', dat2, 'label2', 'title')
-
-    ax = plt.gca()
-    assert ax.has_data()
+    plot_scatter_2(data1, 'label1', data2, 'label2', 'title')
 
 @plot_test
 def test_plot_hist(skip_if_no_mpl):
 
-    dat = np.random.randint(0, 100, 100)
-    plot_hist(dat, 'label', 'title')
+    data = np.random.randint(0, 100, 100)
+    plot_hist(data, 'label', 'title')
diff --git a/fooof/tests/plts/test_utils.py b/fooof/tests/plts/test_utils.py
index 51a2117f4..e7b2c5abb 100644
--- a/fooof/tests/plts/test_utils.py
+++ b/fooof/tests/plts/test_utils.py
@@ -61,7 +61,7 @@ def test_check_plot_kwargs(skip_if_no_mpl):
     plot_kwargs_out = check_plot_kwargs(plot_kwargs, defaults)
     assert plot_kwargs_out == defaults
 
-    # Check it keeps orignal values, and updates to defaults parameters when missing
+    # Check it keeps original values, and updates to defaults parameters when missing
     plot_kwargs = {'alpha' : 0.5}
     defaults = {'alpha' : 1, 'linewidth' : 2}
     plot_kwargs = check_plot_kwargs(plot_kwargs, defaults)
diff --git a/fooof/utils/io.py b/fooof/utils/io.py
index d931bea1e..3c2449a46 100644
--- a/fooof/utils/io.py
+++ b/fooof/utils/io.py
@@ -1,4 +1,4 @@
-"""Utilities for input / ouput for data and models."""
+"""Utilities for input / output for data and models."""
 
 ###################################################################################################
 ###################################################################################################