I've been the subject of gossip a few times that I know of that has reached my ears
You've reminded me, MrsJones - me too. The elders approached me officially accusing me (incorrectly) of wrongdoing because a 'sister' (who I never mixed with) had reported me. I later (accidently) found out who she was. I have no idea why she made up stupid allegations - and I have no idea why the elders would act on silly rumour.
I've heard JWs criticise 'Worldly' people for such things as fornication and adultery, and have responded, ''well Sister so-and-so (or whatever) is guilty of the same''...BUT ''sister so-and-so is sorry''...''How do you know that 'Worldly' person doesn't regret their sin?''.