Only had a few such experiences, but a couple of those did feel more intense to me as the thrill of doing something we shouldn't was exciting. The more intense ones were when it was with someone my other half knew very well.
Cheating or swinging carries a bit of taboo which can increase arousal and make the sex even more fun. At least it does for me. I suspect this is part of why so many women want to get fucked by a BBC. That taboo factor and a big black cock provides lots of mental stimulation and it might be even better when you actually do it.
