In Chapter Three of To Kill a Mockingbird, Calpurnia teaches Scout that everyone, no matter their social standing or the way they are viewed by common society, deserves to be treated with respect. Walter Cunningham, who came to school with no lunch due to his family's extreme poverty, was invited to dinner by Jem Finch. Scout was shocked when Walter "poured syrup on his vegetables and meat with a generous hand" and expressed her surprise vocally. However, Calpurnia, Atticus, and Jem obviously knew that Walter had been reluctant to come at all and that he needed encouragement in order to feel comfortable and fill his stomach. His family was extremely poor, but they did the best they could to repay their debts and did not take "handouts."
When Scout voiced her opinion of Walter's table manners, Calpurnia was furious; she knew not only that Walter was not to blame for his circumstances, but that it was imperative that he retain his impression of being a guest in the Finch home, which he was. Calpurnia had no tolerance for Scout's behavior toward another human being based on his acting differently.
..."There's some folks who don't eat like us," she whispered fiercely, "but you ain't called on to contradict 'em at the table when they don't. That boy's yo' comp'ny and if he wants to eat up the table cloth you let him, you hear?"
"He ain't company, Cal, he's just a Cunningham--"
"Hush your mouth! Don't matter who they are, anybody sets foot in this house's yo' comp'ny, and don't you let me catch you remarkin' on their ways like you was so high and mighty! Yo' folks might be better'n the Cunninghams but it don't count for nothin' the way you're disgracin' 'em--if you can't act fit to eat at the table you can just set here and eat in the kitchen!"
It should be noted that, as a member of Maycomb's African-American community, Calpurnia certainly knew the implications of being looked at as less than others.