In A Streetcar Named Desire, Stanley's resentment of Blanche is a significant part of his character.
Blanche views Stanley in a negative light. She says to Stella that he is "not the type to go for jasmine perfume," and communicates that Stanley is of a lower or almost "bestial" element. Blanche feels that Stanley is not worthy of being associated with the Du Bois name.
Over the course of the drama, Stanley understands what Blanche is trying to do. In response to her constant criticism of his ethnicity by calling him a "Polack," he speaks with scorn to Blanche: "I am not a Polack. People from Poland are Poles, not Polacks. But what I am is a one hundred percent American, born and raised in the greatest country on earth and proud as hell of it, so don’t ever call me a Polack." Stanley does not like the way that Blanche refers to him and the inferiority with which she views him. He realizes that Blanche is using his ethnic background as a way to discredit and insult him. This resentment is echoed when Stanley argues that he is an "American." When he rebukes her, Stanley's resentment towards Blanche is clearly displayed.