Wow, I don't get it. I wouldn't care, if I were in that class. Different people react differently to the same social cues, though of course there is a cultural component (and I am not american). I say to hell with those people, go dance and enjoy yourself. No need to dress differently. In time, they'll come to realize you're not actually a ***** or slut, but just a human being. Maybe there are one or two people there who don't mind, either.

I'd suggest showing compassion when possible. If you are seen as kind, maybe they'll forgive your 'flaw'.