As an early twenties female who regularly goes out to clubs:
I can't talk. I'm virtually a mute, but I can whisper a little, barely. You'd be surprised what passes in a club scene though... you take the effort to whisper close in a guy's ear, and he thinks you're doing it to flirt, not that you actually -have- to, generally speaking. Most of the rest you can do with the right smile, eyes and body language.
However, I a lot of the time go to enjoy the atmosphere and vibe a little... this means that sometimes, I'm not interested in being appraoched by anyone, and if someone does, I'll brush them off wihtout saying anything (because, as I mentioned above... if I took the effort to say something, it would seem like I was flirting, or being coy, no matter what I actually said). It makes some people think I'm horribly rude, but that's the alternative.
Sometimes, when I am interested in other people, I'm not looking for a guy. I might be in the market for a nice looking convincable girl that night, so again, a boy would receive an immediate brush off.
When I am after a guy, it's only ever for one reason, and dancing is not it. We might dance, but that's just foreplay. I'll pick the guy I want, and ignore guys I'm not interested in... if I don't look at you, and I don't feel like you're what I need that night, then there's pretty much nothing you're going to be able to do to change my mind. It's that simple, unfortunately.
So, despite my disadvantage, I don't actually have any confidence issues: I know that I'm very easy on the eyes for most people who are interested in females, and I know I'm a good mover... and I know that if I get to the point with somenoe where I'm undressed enough that they're going to be able to see the scarring on my neck, then I'll already have made sure they're not going to be put off by it, or else they won't see it.
So, all told, chances of me being intersted in what you have to say if you, as guy interested in dancing, appraoch me in a club? Very slim. I'm there for my own reasons, and I'll work out long before you talk to me, whether you feature in them.
I am just one person though, and the point of the mini-rant is that everyone else is just one person as well... Ech different and each with their own resons, wants or needs. There is no "girls are" "women want" or "all guys think", and anyone who pretends there is, or thinks there is, is deluding themselves.
-Harla