Okay, okay. A lot of people say to not judge a book by its cover, but what can I say? Everyone does that, and you've gotta admit that that's true.
In my opinion, I think the saying isn't completely rubbish.. after all, it's wrong to judge, but there's nothing wrong with forming opinions or analyzing from looking at a cover, which I think most readers do. (However, there are those 'readers' that just read books because of their pretty covers and for the sake of reading a book-- tbh those readers are not very readeriffic)
When you pick up a book, I think the cover is the first thing you look at, right? Well, at least I think that's true for at least 90% of people.
Even if it's wrong to judge a book by its cover, I'm not saying that covers don't matter. Like, let me just say, an ugly-butt cover won't get the book anywhere unless the reader doesn't care about the cover at all (which is rare). The cover is what actually draws the reader to a book in the first place, and get them to pick it up. If they want to form opinions, judge, or analyze, or whatever, that's their decision. If they like the synopsis then they'll give the book a try! See, that's why a cover's so important.
I'll admit that most of the books I've read have pretty covers. And that's probably due to my pretty-cover obsession, or it's just simply because the covers are gorgeous and attract lots of people.
The saying "Don't Judge a Book by its Cover" isn't rubbish, not really.