The fake review problem on Amazon is much bigger than people think. Here are my two anecdotes: 1. I got bluetooth headphones on amazon (~$65). They had great reviews, but were very disappointing. I returned them and gave 2 star review. Representative from the manufacturer contacted me and offered me a pair for free. After I got them, they asked for positive review. I refused. That manipulation technique wasn't enough…
Paid reviews from professionals are more dangerous. I just have to hope the companies' greed prevents them from paying enough for a good review.