While thinking about my last blog post and feeling weird about the broad conclusions I implied (that RME is an Impeccable Arbiter of Literary Taste and the people responsible for Amazon ratings are dumb) it occurred to me exactly what an Amazon rating is: an indicator of just how closely a book hews to the reader's expectations for it. The cozy mystery earned its five stars because it is flawlessly cozy, while On Beauty was read by people who'd had widely varying ideas about what they were getting into. It's a strange, idiosyncratic novel that, to me, was so much fun in part because of the way it upended my expectations. Of course, there's a reason "idiosyncratic" isn't much used as a marketing term.
Which, incidentally, explains the popularity of McDonald's, too: if nothing else, it is at least always perfectly McDonald'sy.
Though I have been careful to avoid reading Amazon reviews of my own book, I did once stumble upon a negative review that said my book sucked because "it wasn't even scary." That's pretty easy criticism to accept, since I hadn't tried to make it scary. If only all criticism were like that.