Yelp continues to have problems. They have an algorithm that purportedly decides which reviews are displayed and which are removed, and yet there is something not right about Yelp. I'm not the only one who has noticed that there are many "obviously" fake reviews and there is a lot of annecdotal evidence that if one buys advertising bad reviews can be removed. I have not experienced that but I have heard many first hand complaints.
According to Jeremy Stoppelman, Yelp's CEO: "It's normal for a merchant to see the number of its reviews rise or fall from day to day, and for reviews to mysteriously disappear." "That's normal. It's part of how Yelp works," he said. The reason we do that is to show only the most trusted content. It's nothing nefarious.
"The timing of reviews that appear or disappear after a merchant accepts or declines an advertising contract is purely coincidental, Stoppelman said. He acknowledged that there can be false positives, in which legitimate reviews are removed.:
Yelp's credibility problem: Blame it on algorithm?