Instruct: Classify Amazon reviews into positive or negative sentiment
Query: The author of this book should be ashamed.

Potential book buyer: read the reviews on this book very carefully. All positive reviews have been secretly written by the same person under different names. Just click on the user's name and look to see if they've written other reviews...nope, they haven't since ALL THE POSITIVE REVIEWS FOR THE BOOK HAVE CLEARLY BEEN WRITTEN BY THE AUTHOR.Worse still, this guy shamelessly plugs his book by writing book "reviews" on the listings for more famous and far more useful books like Rich Dad, Poor Dad and the Millionaire Next Door.