You know the saying: "You can't always judge a book by its cover." To that I say - bollocks. Whether literally looking at a book, or figuratively looking at a person, what you see is strongly indicative of what lies beneath.
Publishing is an intricate business, one that most brand-new authors don't understand. Lured by the ease of self-publishing, they write what they are certain is the next great American novel, slap together a cover on their computer, and toss the mess up on Amazon. Then they are shocked when nothing happens.
There are twelve million books on Amazon. Twelve. Million. And growing. How can a consumer possibly be savvy in that ocean of words? Look at the covers. While a beautifully designed cover does not guarantee that the narrative inside will be wonderful, at least the reader knows the author cared enough about their product to put its best face forward.
Conversely, a pixelated or fuzzy photo plus a standard Word font pretty much guarantees the author has never bothered to do research in a bookstore. I wouldn't expect they bothered to learn much about good writing, either.
So what should the reader look for? What makes a good cover?
1. Does it catch your eye with a clear, indicative image?
While the book itself is verbal, its cover lives in a visual environment. The cover image should reflect the genre and style of the interior. Is the key photo element dominant on the cover? Was it professionally photographed? If there is a live model, is it one you have seen on dozens of covers before, or has the author chosen originality?
If there is more than one image, are the photos blended professionally? Do they make one cohesive collage? Or are they cut-and-pasted awkwardly from a variety of sources? Do they assault the eye, or entice it?
If an author chooses to use original artwork (a very risky choice) has the artwork been done professionally - as opposed to a friend's amateur acrylic-painted efforts? Or worse, is it magic marker, crayon, or No. 2 pencil on crumpled paper? Yep. Seen them all.
2. Is the title easily readable?
Is the title font a custom font, not a standard-issue Word choice? Is it large and well-placed on the cover, as opposed to slanting, stacking vertically, or obscuring the image? Do the color and style of the text coordinate with the cover image or compete with it? Does the font reflect the genre, setting, and target audience?
If there is a subtitle, is it short and in a different, smaller font so it's noticeably secondary information? And by the way, if the cover states "A Novel" beneath the title, then you are probably looking at a pretentious amateur effort.
3. Is the author's name clear?
The author's name should also be in a large easy-to-read font; using a standard serif font (the ones with pointy parts) is more acceptable here than it is for the title. But if the cover says "By" Name O'Author, you are once again looking at an amateur piece of work. Real books by real authors from real publishers don't say "by."
4. Does the overall design let you know what's inside?
If you, as a reader, can't discern from the cover the book's genre, era/setting, and something about the plot or characters, then the cover has not done its job. And if the cover looks painfully awkward, steer clear. Spend your hard-earned cash on a product which honors the reader, not one which insults them.
I subscribe to an equally hilarious and terrifying site, LousyBookCovers.com. Several times a day, new covers are posted which make me shudder, cringe, and slap my forehead in disbelief. Sad to say, I personally know six authors, and one over-exposed cover model, who have been featured there.
When their covers showed up, I did tell them. After all, if one of my covers was called "lousy" I'd want to know - and then I would change it! Only one of them chose to make changes, however. They all shrugged and said, "Any publicity is good publicity."