This happens a lot in China. They call it the "human flesh search engine". Very scary, because it works very well. Unfortunately it permanently damages people's lives.
The real answer here is escrow with multisig. What you are suggesting could cause very negative publicity for the bitcoin community. Interesting idea, but I wouldn't recommend it.
I think it could have the opposite effect. People assume scammers exist in any community/group and tend to think everyone else is trying to get over on them. This could provide a sense of comfort that there is a watchman to the wild west.
