Agree this happens all the time at conferences and on business trips. IME, it wasn't always limited to the chaps you'd expect it from.
I used to work with two men, and we all did alot of business travel. I found it very difficult to socialise with them/their wives when I knew what the husbands had got up to on the road. I felt an accomplice somehow, as I was contributing to the deception by pretending it had never happened.
I think lots of people can compartmentalise what happens away from home. There's also the "advantage" of probably not bumping into someone who you know, and also there is little chance of a fling being anything other than just that. So, the chance of repercussions is seriously reduced. Add in a bit of alcohol/reduced inhibitions, and it happens far too often.