This is a 4-year-old article, and I only found it because Facebook suggested it to me after a friend was talking about her bad experiences on OKCupid.
But it's really interesting.
A guy decided to test two theories:
1) That females have a huge edge over men on dating sites, at least as far as receiving messages in response to their profile
2) That attractive people of both genders also have a huge edge on dating sites over average looking and ugly people
He made 10 identical profiles. The only difference was that 5 were male, 5 were female, and their pics were all different.
http://jonmillward.com/blog/attracti...ng-experiment/
Results are pretty much what you'd expect, but still fascinating.