Known Ninja Group Alerter
 

I'm looking for a mod that will alert me to known ninja'ers on servers if I group with them.

I'm looking for something that is updated by itself, either through a database or through "blacklist updates" so I don't have to mark already known Ninjas. It should allow me to mark new people and propagate to other users using the addon to warn them as well. Perhaps it wouldn't trigger for other users until x number of people have reported him, instead warning you locally before that.

Is this even possible?

Karma, BadApples, and BadPlayer come to mind, although I know there are more. No way (that I know of) to share amongst every player, but some of these addons will sync with guildmates and /or friends.