I've run into a problem with clearResults in IE only. In IE when you submit the form by selecting an item (itemSelect or itemFocus) in IE and then use the browser back button the field is not emptied (still contains the selected text) . This does not happen in FF or other browsers.
I've tested it in IE7, IE8 and IE9... in all three versions the field is not emptied when you user the browser back button after clicking on an item in the list to submit the form.
The problem does not occur in FF, Chrome and Safari.