It… Depends. When buying a book in the bookstore, I tend to be very wary. I read a lot of sci-fi / fantasy, which tends to have fantastic covers… That more often than not say nothing of the quality of the book
When reading online, I actually pay a lot of attention to the covers. A very poor quality cover often means that the author is not invested in the story - if they can’t be bothered with it, they often can’t be bothered with their writing, either. On the other hand, if a cover is a stolen copyright image, I drop it immediately. I have too many artist friends to condone art theft.
Authors who made their own cover - or commissioned one from an artist - get a definite head start with me, though. It show clear effort and investment in their work, which makes me want to appreciate it