This is a great idea!
I agree that there shouldn't be a "black list" made.
I have seen negative comments made about companies I currently work for, who I have never had problems with.
Personally what I am doing, is keeping my own list, when I read things on SOT about companies not paying I add them to my list, so if I get a call from any of them I can make a decision as to whether I want to take their work or not. I also note how many times there have been postings about each company.
That is my personal solution to this, if the company doesn't advertise on SOT.