In order to understand what is a bad book cover, we can start by figuring out what is a good one instead. Renowned book designer Chip Kidd (who created the cover for Jurassic Park and many others), said that book design is all about giving form to content but also appreciating the balance between the two.

In his Ted talk, Kidd explained that on his first day of graphic design class in school, the teacher drew a picture of an apple, then wrote the word Apple and said: "Listen up. You either say this," pointing to the word apple, "or you can show this," pointing to the picture of the apple.

"But you don't do this," he said, pointing to a picture of an apple with the word Apple beneath it. "Because this is treating your audience like a moron. And they deserve better."

So a book cover can show or tell, but can't do both.

Best-selling author Jeff Goins thinks covers should also know and respect the audience of the book.

"Books are not created in a vacuum. They are not merely a manifestation of the author's creativity. The content needs a form, and the form will influence the way the content is consumed," Goins wrote. "All art has an audience, and books are no different. Good book design, then, is not just an expression of the story or idea behind a book. It is a piece of the marketing. As such, it needs to matter to the people it was intended for."

Coming back to Chip Kidd, he said that a book designer has a responsibility to three groups of people: the reader, the publisher, and the author. So the ultimate goal of a good book design is to get people to respond. For the reader, you want people to say, "Wow! I need to read that." For the publisher, you want them to say, "This is something we can print." And for the author, you want them to say, "Yes! This expresses my idea better than I could!"

So I guess you could say that a terrible book design is boring, unmarketable, and superficial.