A recent glitch at Amazon shows how the review system is abused by people who have a vested interest in boosting sales with a positive review. Happily, the article mentions this:
Many prolific reviewers speculate that Harriet Klausner, 55, who has long reigned as No. 1, cannot possible read all the books she reviews. In a telephone interview, Klausner, in turn, accused the No. 2 reviewer of getting people to vote for him and against her in a “desperate attempt to be No. 1.”
Me-ow! It’s about time someone noticed. And, in my opinion, it is not speculation. It’s cold, hard math.