I don't condone true cheating, so, no, I don't really pursue them. I will flirt, though. No harm in flirting lol now if "cheating" is part of their dynamic, then I don't mind one bit. It's a form of consensual non-consent, and that in okay with. All that said I nearly fucked a married coworker last year. I found her just so irresistible. But she had second thoughts, and stopped it. That's the one time I have fully and willingly pursued a married woman (outside of harmless flirting) who's husband didn't know.
As for single FWB, no, generally not either, although I'm not against it. I just have had too many bad experiences with single FWB before, so I'm much more picky in regards to single women. They always seem to get possessive or start catching feelings, or they were lying to me and broke our agreement. I haven't wanted feelings for some time, so I generally just stick to couples and married women. They are safer in every regard when it comes to sexual partners. Although I had a single lady as a FWB that just recently moved away. We'd been off and on FWB for like 3 years now, and she's the one and only that I've been with that truly understands what FWB means.
All that said I'm not at all against either one. I just really fucking enjoy fucking married/taken women lol