I don't like it, but it works, to an extent. I've found when someone I like is actually really nice to me and pays me a lot of attention, I go off them a little bit, just for a while. It feels like they've lost some of their attractiveness because, if they're interested in me, they must not be as great as I thought they were, which I think is to do with your own self-esteem and self-image. When someone's being more difficult, I think it makes your feelings for them stronger - you always want what you can't have. But after a bit, it just gets annoying. If it goes on for too long, you just think, 'Stuff it, it's never gonna happen, I'm fed up of this' and try to move on, so it can backfire.
i also hate when genuine dislike, or even contempt, is misinterpreted as playing hard to get! It's like, no, I actually do hate you!