Yelp has been having problems for a long time, especially with small business owners. The site is killing small business owners, just do a Google search and you will find endless complaints about the site. Truth is Yelp cannot control the reviews, they can't guarantee them and their Filter... if it works only 50% of the time then it is worthless.
Thanks for the feedback! We're looking to present a different way of looking for local businesses. We want our site to feature "the best of the best" so in order to do that we need to invite more positive reviews. Constructive feedback is definitely positive as well and we invite users to submit their feedback, which in turn goes directly to the business owners to encourage change. We're not trying to be another site of 3-star restaurants and C-average businesses.