Reality just hit me hard...is he only flirting because he heard i was a "slut"?

Yesterday a guy I've liked for a while was flirting with me (its in my last question). At school everyone thinks I'm a tramp for no reason. I'm really not and it always attracts loser guys and players. My problem is that i just realized the guy I'm crushing on might only be flirting with me because i was talking to some girl and said "everyone calls me a tramp anyway..." and he was listening and said something when he wasn't really part of the conversation (he doesn't go to my school so he didn't know what people said about me). This is the first time he's shown real interest me (after i said this) and I'm a little pissed! Do you think he's just flirting because he thinks I'm a ?