This is such an interesting topic! I don't think I can say anything more that has not been said before, but here is my two-cents-worth. I have a very strong idea of what I want to read and don't. Negative reviews actually excite and challenge me, especially if it is about a book I had already targeted. I'm a genre reader mainly so any new book under my preferred genre I will be interested in.

Negative reviews may affect book sales, but readers are not in the business of selling books, are they? We read books and if we feel so inclined write whether we liked the book or not.

As to professional reviews - sometimes I read them, because they can be fun to read but I have never been swayed by them. These reviews could very well have been written by alien life forms, for all I know. I don't have a personal connection with professional book reviewers.

I trust book recommendations from fellow book bloggers and book club members. I love reading the reviews by other readers. My TBR pile has grown monstrous because of the honest opinion of these people.

The auto-generated recommendations based on browsing and purchase history may be soulless but it sure is useful in bringing to my attention books I may be interested in. So I like Amazon, Shelfari, and other book sites.