Many online reviews have a helpfulness rating, and such ratings are being widely used by online shoppers for shopping research. Researchers also use them as a review quality benchmark. However, there is scant research about the reliability of such ratings. This paper explores the reliability of helpfulness ratings and their resistance to manipulations. We found that the existing helpfulness ratings for most helpful reviews are inflated and significantly higher than ratings we collected from a random population due to online shopper self-selection behavior. We also found existing helpfulness ratings for most helpful favorable reviews have an anchoring effect on subsequent votes, thus could be potentially manipulated to boost sales. In contrast, ratings for most helpful critical reviews have a counter-anchoring effect due to risk aversion, thus could backfire if manipulated. Implications and future research are discussed.