Scout learns a lesson early in the novel when she makes fun of Walter Cunningham Jr., saying he is "just a Cunningham" and therefore wouldn't need to be that polite to him. She apparently has learned (not from Atticus) that the poorer people don't need to be treated as well as those whose families have a history of higher social class. Cal and Atticus disabuse her of this idea, but in general, judging people in terms of income and social class is a problem/tradition in Maycomb.
We can see how Tom Robinson is stereotyped at the trial, namely by Bob and Mayella Ewell. They come across as racist, pro-slavery, hateful people who really think that black people are inferior to whites. Mr. Gilmer also treats Tom like an inferior, which either shows his own biases or this is simply part of his strategy to convict Tom. Gilmer refers to Tom as "boy," a racial slur especially when addressing a grown man. Gilmer is condescending, again perhaps as a means of strategy, but it also suggests an heir of superiority that he talks down to Tom. Gilmer (and other racists of the town) thereby reinforce the stereotype of how racists actually think; in other words, by stereotyping Tom, they stereotype themselves (accurately) as small-minded racists.
Maycomb is rich in traditional gender roles and Scout wants nothing to do with this. This is clear in Chapter 24 when Aunt Alexandra makes Scout attend her meeting and behave like a lady. We might call these ladies stereotypical "southern belles" - southern women of the upper classes. This term is used as a positive compliment, but can have negative connotations such as upper class women who believe and behave like elitists. This is clearly the case with Mrs. Merriweather who is a total hypocrite; praising missionary work in Africa, but intent on keeping African-Americans in their place in Maycomb. Scout doesn't buy into these stereotypical roles of femininity, but at the end of the chapter she decides that a lady is strong in times of crisis, oddly enough learning this from Aunt Alexandra.