Of course some reviews are real, and there's an art to deciphering the wheat from the chaff. The problem is that there's the constant pressure you describe to drown out legitimate reviews or otherwise game the system, so that 'art' becomes more and more tricky and less reliable. I gave up on reading the Yelp tea leaves a long time ago, and other prominent ones like Google Maps and Tripadvisor have been getting worse over time. I can still usually intuit my way through Amazon and and Steam reviews, if there's enough reviews and I take my time.