Thanks for letting me know the reason. I worry that the problem with this is the fact that the username can be changed so quickly and easily.
In this case enough hell was raised that people knew to watch out for "blkhole," but then he changed his name to "mobyluv" and people bought from him again.
In fact people who were responding to the blkhole is bad threads found themselves dealing with "mobyluv"
So that might be something that may need to be addressed... (Which I state respectfully, I know a lot of work has gone into this site for many years and it is free)
On the other hand I don't know how often something like this happens. It may not be worth the trouble of dealing with usernames and such.