The name pretty much says it all. I am interested to see the responses this thread will get and the general response to those responses.

Please, do not concern yourself with when women are cheating, as this is not about women, and I'm pretty sure you could find several examples here and some of them pretty brutal (any flair actually) and solipsistic.

What I want to know is how you, as men, regard it, when it's done by other men and the notion of cheating in general. Would you willing to do it, and what are the conditions that would make you do it?