Let’s let the tamale-vendor at the end of Scene Two sum this up for us: "RED-HOT!" Stanley, a.k.a. "the gaudy seed-bearer," is very sexual. Stella is all about the virility popping out of his veins, and is attracted to his violent streak. Even Blanche experiences sexual tension with him, and she seems to spend a good amount of the play telling Stanley not to undress any further in front of her.
Of course, Williams also presents the darker side of sex during the rape scene at the end of the play. Stella might think the Stanley's aggressive nature is sexy, but Streetcar sides with the more delicate Blanche in condemning sexual violence.