Meh. A cover might catch my eye in a print bookstore, but I don't care with e-books. Most of my nonfiction reads, I end up finding because they're recommended via searches; some via reviews or personal recommendations.
For practical use, it can be helpful to have a cover to search for when scrolling through a big e-library. In that case, though, I need only recognize the cover; I don't care whether it's attractive.
I'm reading a book on North Korea today, which I just bought, and I can't remember what the cover looks like at all. I read one on China yesterday, and all I remember is there was some kinda red rectangle splotched on the cover.