As far as the parity of cheating, realize that most men feel that if they've touched some part of a woman thats normally covered by clothes, that "something happened". Some people, both men and women, feel that sex without any emotional attachment isnt cheating. Then of course, we get the "clinton effect" where oral sex isnt really sex, hence it isnt cheating.
I've actually heard some guys say that if they used a condom, that its not cheating because there was no direct contact.
I've heard some women talk about sleeping with three guys, but they really only cared about one of them, so the other two didnt mean anything, and therefore no cheating. I've heard a couple who were having sex with a guy who was paying them money afterwards...get mad because the guy never took them out for dinner or drinks. One said "Considering the stuff the guy does to me, you'd think he'd get me a little drunk first". When I asked why she continued seeing him she said "I need his gifts, he's very generous".
She was totally a ho, and she didnt even realize it. He was just a boyfriend who paid her and didnt take her anywhere, and only showed up for sex and left afterwards. Right.
Now are we starting to get a little bit of an idea why surveys/polls, especially involving sex, tend to be a little bit problematic?