With regards to customer ratings in principle I think that would be a good idea, buyer credibility is often only backed up by their forum profile and purchasing stats and the two are not necessarily linked as many like to keep them separate. Of course some vendors automatically unfairly call some buyers scammers etc when disputes arise the same as some buyers do to vendors. Anything that helps improve the situation though is a good thing as there are a small number of people causing issues for the many, not sure if that will ever be totally rooted out though.