It's not a review that says your book sucks. That's an opinion, and one that the writer is entirely entitled to.
It's a review that is negative based on something UTTERLY IRRELEVANT TO THE BOOK ITSELF.
Why do I bring this up?
Because I noticed just such a review for Threshold today. Someone reviewed it and gave it one star.
So I scrolled down to look, figuring I was in for another marvelous ripping for cardboard characters, or someone hated the science, or my insensitive portrayal of Aussies or Irish had blown someone's gaskets.
But no, they're rating the book at 1 star because... there's no Kindle edition.
This has of course nothing to do with the book at all.
That's the only kind of review that really annoys me.