Sometimes I read a fic that stays with me, that I can't stop thinking about. It gets its hooks in me.
But if there's something significant about it that seems flawed (characterisation, plot, language use, whatever), I hesitate to rec it.
I read and enjoy a lot of fics. but usually only rec fics that are most compelling to me personally.
When I find a fic compelling enough to want to rec it, and it also has certain kinds of flaws, I usually don't rec.