Do you think some married men simply like to flirt, or do you think flirting is a sign s/he would go further, if given the opportunity?

I think people project their own morals onto others. If you would take advantage of the opportunity, then you propably think others would also.
The ones with more conservative morals don't even consider the exchanges as "opportunities."
I will say, I've always enjoyed a fun/playful interaction with people (esp cute females,), but I'm sure I'd never take it any further than the convo.
Does my ego enjoy the boost, though? Absolutely!!