Because I have lived 41 years on this planet and I have experienced how the world works. If we're talking about averages, your average male is waaaay more willing to ignore traits that he dislikes on a female in order to have a one night stand, than the opposite. It's basic evolutionary biology.

You have no proof and it's not cool

I think it’s completely clear in my experience that men are much more willing to throw standards out the window for a hook up.