>I am definitely guilty of judging a book by its cover.

I mean, that's what they are designed for! Covers are usually pretty good for assessing stuff like the genre of the book, the age group, the overall 'tone' of the book, the sort of authors they're trying to align the book with, etc.

But they can't tell you much about the quality of the writing or if you'll connect with the story.

Reviews are good. I personally have found it helpful to read a few paragraphs. But we're all going to end up picking up bad books now and again.