After reviewing some user's first answers, occasionally I'll come across that flat-out insult or slur that I know they'll most likely have their account deactivated. After that user is banned, they'll have that greyed-out avatar:
Do I get reputation back from any of their posts that I downvoted?
Related to this is "Do I get my reputation refunded if a bad answer gets deleted?" - it covers deleting answers, but not deactivated users.