Let's get this out of the way: I've been guilty of emotional rating TONS of times. I try my utmost hardest to be a fair reviewer, but sometimes there is that one book that you can't help but feel passionately about, whether it be positive or negative passion.
What exactly
is emotional rating? Well, according to
Summer's Very Important and Very Accurate Dictionary, it's done by book reviewers when all reason is thrown to the wind and emotion is trusted to assign a book a rating.
There's two scenarios: one, a book that you know has bad writing, bad characterization, etc, but you follow what the book made you
feel and bestow upon it a 5-star rating. Or, on the other hand, you know a book has a great plot and the writing is amazing but there's that one character that grinds your gears and makes you so
angry that you had to give the book 1 star.
While I do do this (quite a lot, actually) in my defense I usually state in my review the goods and the bads regardless of my feelings about the book overall. With that said, I don't bother with reviews for a lot of the non-review books I read, so I wouldn't trust those if I were you. :3