As Editor of the book reviewing and author interviewing site, bookpleasures.com, I am apalled when I learn that some authors have been shafted by "fake" book reviewers. These reviewers are only interested in receiving a complimentary book and unfortunately very rarely write a review.
As the old cliché goes- let the buyer beware. Before agreeing to have your book reviewed, make sure you know something about the reviewer and where the review will be posted. Insist that you have samples of previous reviews. Also, check and see the genre that are reviewed and if it is a site like bookpleasures.com, check out who are the reviewers.
I receive hundreds of requests for reviews every month and I tell the individual requesting the review not to send out any books until he or she hears from myself or one of my reviewers.
Norm, Editor Bookpleasures.com