This has been my experience in so far as the man is married. As a cross dresser I get even more turned on seeing that wedding ring and thinking "he could be fucking his wife be he chose to let me satisfy him with my mouth rather than fuck her." It may not be the case, but I like to think that way.Most married men are looking for something their wives won't give them - typically oral sex to completion.
The convenient parts about blowing a married man is that he's probably not going to tell all his buddies about it - and the minute he's fed you his hot load, he's going to hurry home to wifey --- so remember to lick the tip clean when you're done so she won't suspect !!