I found out today after losing 100 rep (probably one of the users of playorm who asks a lot of questions I imagine) that when a user is removed, I lose all the rep I gained from that user. It kinda bites but oh well.
It however took me a while to figure out what this meant and why I lost the reputation. Turning the "User removed" message in the reputation history into a link leading to a (or the canonical) Meta post containing an explanation, might help avoid this confusion. It would have prevented me from spending 15 minutes of my time trying to figure out why this happened.