A woman on Money Talks News writes: "My niche was book reviews. PR firms would hire me to post five-star reviews on high-profile sites like Amazon and Barnes & Noble in order to create a buzz. While they didn’t require me to write lies or tell me exactly what to write, if the review wasn’t five star, they didn’t pay the typical $10- 20 fee."
Read more here.
And the New York Times takes a longer look at fake reviews in general here.