If you'd asked me a year ago whether published authors read the amazon reviews of their books I'd have laughed and said 'No of course not.' Turns out I was wrong about that, it appears that, some at least, not only read them but obsess over them. This was, in all seriousness, a major surprise to me.
Partly this is because I rarely read the reviews of a non-fiction book I'm considering buying and have never, ever read the amazon reviews of a novel before buying it, (I mean, there might be spoilers and how do I know which of the random folks reviewing the book share my taste in fiction? I have on occasion read the reviews of a novel I've already read to see if other people agree with me about it, but that's not really the point here).
Obviously people's buying habits vary, so maybe there are people who read every single review before handing over their cash, but on the other hand customer reviews are a pretty long way down the page which tells you something about how important amazon thinks that information is to making a sale.
My point is that I didn't expect authors to read amazon reviews because I don't rate them as being particularly important or informed and if nothing else you only get to see them if you've already found your way to the book's page (unless there's some other way to see them that I, as a casual customer, don't know about) essentially they're preaching, if not to the choir, then at least to the congregation.
However, the main reason I didn't expect authors to read their amazon reviews is because, well, it seems kind of creepy, like eavesdropping to find out what people say about you behind your back. The thing is, it's my belief (and I may be wrong about this) that the majority of amazon reviews are written, not for the benefit of the author, but for the benefit of potential readers. To me it seems as if someone with something to say to the author of a book would do it somewhere dedicated to the author, a fan site, the author's personal website, something like that. Writing a review on a shopping site seems more under the heading of consumer services (much like contributing to wikipedia on a subject you're knowledgeable about is often motivated by the desire to help people who want to know about said subject, but don't). This seems obvious to me, so obvious I'd never consciously thought about it (which doesn't of course mean I'm right), or rather, it did, right up until I heard (or rather read, it was on twitter) a writer ask why anyone would write a two star review.
I was, I have to admit, stumped, if I'd had an immediate answer maybe I'd have replied (or maybe not), but in my gut I knew that writing a two star review was a perfectly reasonable thing to do, I just had to figure out how to put that feeling into words. So I went away and thought about it and this is what I came up with:
The reason to write a two star review (or at least a reason) is that 'this book isn't terrible but it's nothing special either' is valid and helpful consumer advice (or it can be if you accompany it with your reasons for thinking that), and if what you care about isn't the book itself (or by extension, the author that wrote it), but the people that might be considering buying it, then taking the time to give an honest opinion is just as worth it, regardless of what that opinion actually is.