I know there's a mechanism in place to monitor and remove serial downvotes against a single user, but earlier today a thread received a downvote on the question and every single answer with no specific reason why. This also got me thinking about visibility downvoting - it's possible that one answerer received a downvote and retaliated by downvoting everyone else involved in the thread? Is that kind of vengeance downvoting monitored? If not, could it be implemented (+feature-request tag)?
To clarify, I'm talking about detecting that a user is downvoting all other answers (and possibly the question), after he received a downvote on his/her answer.