"User trust is the foundation on which Yelp is built and the reason 31 million consumers turned to the site last month to find a great local business. Today we're announcing two important product changes to reinforce that trust and make it even more clear that Yelp treats review content equally for all businesses, with no connection between advertising and reviews.
Specifically, we're adding the ability to see reviews filtered by our review filter and we're discontinuing the "Favorite Review" feature that's part of our advertising package."
Jeremy - what you need to do is to make certain that the reviews are from real people and are not placed there by companies; and to combat bad, spiteful reviews allow discussions on the comments (comments on the comments). This is not taking into account the "pay-for-play" perception where becoming a paid advertiser on Yelp enables you to remove bad comments and put up good ones.
Yelp is a good idea but falls short in execution.