White people were so poorly educated back then, they used to call black people "Those dirty negroes" all the time. As they got better education, they learned what pleonasm was.
Are you saying all black people are dirty?
Black people are filthy that's why everyone uses those derogatory terms to describe them. Now that the white population has a high level of education, they have learned the meaning of "pleonasm".
Generalizing black people by calling them all dirty is offensive. Many have access to proper bathing options and maintain proper hygiene. Implying otherwise is just a harmful sweeping statement.