This is interesting. I would say it's more likely to be true for girls, in that girls that are worse looking, have less options and so hold onto what they can get, although this would be a massive generalisation and i think would only apply to girls that are well below average.
I would not agree when it comes to men. I am a strong believer that a mans looks have little to do with how attractive he is to women, instead it's much more to do with his personality. The guys who are not good with girls, will hold onto whatever they can get, whereas the guys who know what they are doing have lots of options, and so can be much more picky in who they get into a relationship with.
Come to think of it, i would say that men who are not good with women are much more likely to try and get into a relationship than average looking women, mainly because even average looking women have a lot of sexual power over the majority of guys.