A business I used recently for some tree maintenance in my town had a 1-star Yelp review which was perplexing. In this case, the business and owner are well-known in the area as one of the best at what they do and top subject matter experts.
While digging a little, I found that Yelp was highlighting only the four 1-star reviews and factoring only those into the score. Each of these reviews is responded to by the owner with an explanation, all of which look fairly reasonable to me.
Below this, hidden away under a link and not factored into the score were 15 other reviews that Yelp tagged as 'not currently recommended'. These reviews span a period of 4-5 years+ and are mostly positive 4-5 star reviews. I am no expert but they do not look faked at all to me. Why would this be the case? This business also had 42 5-star reviews on Google. Seems a little odd to me and this really swayed my opinion for good on Yelp.