I think such a list would be more problematic than helpful. Do you just take one person's word that someone is a scammer without the named person being able to have a side to the story? How do you trust the users that are posting to be accurate without verification?
I do agree that it is bad that some people try to get one over others in the game through scamming them from trades and what not. I get that a list of names could be helpful but in reality (as we've probably seen in this thread) it just becomes a way for a user to flame another.
If someone is trying to pull a fast one over you in trade then don't trade with them, by all means tell your friends/guild to keep an eye out, but I don't think publically naming people is a positive thing. It will probably just result in more antagonistic messages and drama than anyone really needs these days.