Unpopular opinion: I do judge books by their covers.
It comes down to one simple reason. If you (or your publisher) didn’t care enough or didn’t want to spend the money to come up with an intriguing, beautiful, genre-appropriate cover, what are the chances that you (or they) cared enough or wanted to spend the money to develop and edit to make the story as perfect and engaging as possible?
In my career and my free time, I spend an enormous amount of time around books.
However, this is not always true — sometimes there’s a crap cover on an amazing book, and sometimes there’s a beautiful cover on a turd of a book — but it usually is a good guideline to follow.
Here’s some book covers that I’m loving lately: