idk. I just find books that sound interesting and then read the negative reviews regardless of the rating/score. I think a book is worth reading if you disagree with the negative reviews or you don't care about the criticisms.

Example: Someone may say that a book is "bad" because "it has too many girls" or "it has coffee in it." Obviously, those are ridiculous reasons, but people DO criticize books for dumb things like that all the time. On the other hand, you do tend to find lots of biases and valid criticisms in the negative reviews. Most positive reviews (unfortunately) talk about how they liked the book, but not WHY they liked the book.