Let us be literal for a moment: we generally judge books by their covers. If the cover is bleh, or just doesn’t suggest the sort of read we’re looking for, we move on. If it intrigues, we take a look inside.
Personally, I’m put off by garish covers with colours that attack each other, depictions of hysterical half-naked people, and convoluted decoration that obscures those all-important details like the title. Also fonts that are so stylized that making the title out is like deciphering your great-aunt’s handwriting.
On the other hand, old leather bindings with gold tooling draw me like a bee to honey, regardless of the actual contents of the book. (Minor Products of the Phillipine Rainforest, Volume II? Well, why not?)
What do you look for in a cover? What engages you, what drives you away?