Crime Fiction writer LH Thompson has found that three-star reviews can kill book sales.
On his blog Death by Typing, he explains the impact of what he calls a “mediocre” reviews.” Check it out:
Most readers probably don’t realize it, but a three-star review can shut someone’s sales right down. Readers, for the most part, only buy four- and five-star books. It doesn’t matter that the reviewer may have meant “it’s good”, rather than, “it’s great” or “it’s a classic.” … On ebook sites, especially market-dominant Amazon, all the data demonstrates the following hierarchy: 1) Five-star or four-and-a-half star books sell well; 2) four-star books sell occasionally; 3) three-and-a-half-star or below books hardly ever sell a copy.