one card FD

If I think I have no other equity, I probably fold anything lower than a King.

I folded red Sevens on flop yesterday with three hearts (A T 5). Four way action BTF in a raised pot and I was in SB. There was a bet and two calls on the flop and of course my flush would have been good.

That would be my take also.

Same here. The tricky situations usually arise when you have a worse flush draw and a pair or a draw. (Think JTo with a J high flush draw on a QT8 monotone flop.)