I've been coming to stackoverflow years before I registered that I decided to partake rather than continue with any more leeching.
Sigh.. realized something about reputation on this site. If anyone notices reputation going down, that doesn't mean the answer you gave was wrong. I found out that users who wish to get their account deleted also gets all their posts removed. So, let's say if you happened to help that user in the past, and that user picked your answer as the one that helped him out, you receive 10 or 25 points. If that user decides to delete that account or delete the post itself, then all answers (including yours) and the points that are associated with it are removed and our reputation goes down and is logged as "loss of reputation".
So when looking at other users profiles, just take the loss of reputation with a grain of salt.