I talked with a friend recently who mentioned being around a bunch of American girls after having been out of the country for a while. One of the girls obviously liked him. Then she started talking to other girls in ear-shot of him about all the guys she'd had sex with.
My friend found this a complete turnoff and lost all interest in the girl. He's no newbie; he's been with a lot of girls. He just does not like this kind of classless, crass behavior. Regardless, he knew this girl was most likely putting on this display to signal sexual availability to him.
I said yeah, I've had a bunch of girls who obviously liked that do that to me over the years... like you, I find it a turnoff. It is mostly American girls I've had do this to me too. Though come to think of it as I write this now I've had a few non-American girls who have done things like this also.
If you like classy girls, you are going to find the behavior above and many of the other behaviors we'll talk about below distasteful. Because what it is is, obviously, a lack of class; the girl has no more refined way to signal her receptiveness or availability to you, so goes for 'crassy' instead of 'classy'.
So let's take a look at some of the various rude, crude, unclassy behaviors girls will engage in that are actually (much of the time) signs of interest / sexual availability signals.
Depending on your classiness preference, you may find these behaviors turnoffs... or they might be right up your alley.