They really have no way of proving whether something is paid. They have a frustrating algorithm that cycles reviews, and filters out new users and inactive users. I will log on yelp at least once a month and review something, share, like, just to keep it active so my reviews stick. Here"s some red flags to avoid New users whose first few reviews include a business that has never been reviewed A review of your own business A significant amount of reviews at any given time Having substantially more reviews than competitors in the same category, I think this is for reviews under a certain review quantity threshold. Having inactive users suddenly log in and review a business with little reviews. Rating everything 5 stars Users who have not completed most of their profile, have friends, and only access a few functions of the site Businesses who have reviews and haven"t completed their profile Conflicting reviews from the same IP address (logging on friends accounts) The truth is that most businesses with low volume or commercial clients will have a very hard time getting reviews, but they still get them whether its friends, family, or paid.. all you can do is try to keep up and compete.