I wonder how many people have read the small print and realise that Amazon owns the copyright on all reviews on their site? For some time, people have wondered why reviews for their books have suddenly gone missing. Sometimes, even the books have vanished, particularly if published to Kindle (but possibly not exclusively). A violation is the probable answer.
You cannot/must not copy a review from Amazon and use it word for word on your own website or in your own promotion. Do not review someone's book and use the same text on Amazon and Goodreads, for example. Amazon's bots will discover the clone and may react by wiping the Amazon version or the book, or your account if you are publisher.
I have received several references to this over the last few weeks. Many people have tried to argue with Amazon, but none have changed their policy so far. This may happen in the future, of course - but at present it's wise to avoid breaking Amazon's terms of service.
Two of my sources of information are Aggie Villanueva:
http://www.promotionalacarteblog.com/2012/02/amazon-still-deleting-books-and-reviews-inexplicably-or-is-there-an-explanation/ (a potentially useful website), and the advertising for a product:
All best wishes
Dont forget, I'll be hosting Sally Murphy and Sonia Kretschmar on March 6 ...look inside Sonia's studio - write a comment to go into the draw for a copy of 'Do Not Forget Australia'.