Yes, that's a good point actually.
For a man to cheat he has to be willing to pay, for a woman the odds are in your favour so you have lots of choice where ever you go.
The advantage of a married dating site is everyone is open about their situation, and most of the profiles state that they aren't looking to change their situation.
This isn't always true, and not true in my case although I didn't know that when I started.
Cheating is addictive. You discover the high of meeting new people, being wanted sexually and often bringing back into your life things that have either disappeared or never been there.
I wouldn't cheat though if I was in the right relationship. In fact, I would never cheat on my affair partner, as ironic as it seems.