Hmm...while I can appreciate the motivation behind the idea, I'd say be careful of this. It could turn into a witch hunt VERY quickly if not controlled. Let's face it, there are some people who have no expectations of vendors (other than their goal to make money), but there are others who's expectations are absolutely unreasonable.
+1
That's gonna turn into a bash fest quicker than you can blink
An eye.
You think it gets bad here where have a bunch of good
Mods to rain things in. Facebook and no
Control will be a disaster of people fighting