well i guess obviously she'd have to be attractive (which goes both ways), but other than that it comes down to how comfortable with herself she is. she has to be her own woman, if that makes any sense, confident but not a bitch. you can tell by how a girl holds herself whether shes a bitch or insecure. a pretty girl who knows how to have fun is hard to pass up..
im sure this has happened to some dudes here, but enough times i'll be hanging out and there might be a girl chilling who i don't think is drop dead gorgeous and at first she's just whatever.. but after hanging out more and finding out shes a ton of fun, she's all of a sudden the only thing i think about.
on the contrary, if your a drop dead gorgeous girl and your a complete bitch.. then i just want in your pants.