there is no need for negative comments about people
Oh how I agree with you on that score! Sadly we seem to be in the minority because there are still some folks who feel they have the right to make negative comments/slag folks off because they are somewhat remote from the person being criticised.
How would you envisage dealing with the situation where 3 postings said that ABC Magic Ltd were an excellent source yet a fourth posting told a different story whereby ABC let them down badly? All four may be factual and truthful depending on the circumstances but that fourth one would have to be carefully worded/moderated in case it went OTT.
Of course, even if there isn't a dedicated 'Trusted List' section, there's no reason why individuals can't tell everyone about good service from a particular supplier or suppliers as we do at the momnent. This topic is well worth further consideration as it's valuable to get other opnions on sources as well as tricks.