Amazon has started to delete thousands of reviews on eBooks per this link:
http://www.nytimes.com/2012/12/23/te...it_th_20121223
It appears lots of those reviews give high ratings to eBooks bu may have been driven by friends, relatives of authors or authors, themselves, using muptiple identities.
Personally, I never rely on eBook reviews and never post my own reviews on any eBooks. I only post reviews on products which I would rate 5 stars for really good or one star for really bad.
When looking at eBook reviews, only read those which say "Amazon Verified Purchaser." At least then one can be sure a real customer of that eBook really read and rated it. Personally, I think, if the eBook was not pruchased from Amazon by the reviewer, it should not be permitted at all.
I rate my eBooks by my interest in biography and history and then place them all in an Excel spreadsheet and sort them by pages per dollar paid. I look for the most pages and the lowest price even if footnotes are included in the pages. Footnotes tend to validate the accuracy of the eBook.