Book covers. Those lovely things that adorn the books we buy, whether they're fantasy, horror or some horribly gushy romance tale that makes you want to throw up. They're marketing tools as much as they are works of art, and they can mislead the customer in the same way they can encourage them. I love book covers more than some, and it influences my purchasing more than the contents of the book can. I love the old style of fantasy covers, the style you see adorning R.A. Salvatore, old Brooks books or even the US copies of Robert Jordan's Wheel of Time. I love that feel they have, the campiness and the sense of heroism. Sometimes they can look poor, but at other times? I'm blown away.
Let's take Robert Jordan's Wheel of Time series. I haven't read the books, but I've certainly got an opinion on the covers. In the UK, he's published by Orbit Books, and they originally printed editions in the same work as the US ones. At some point they stopped doing that, and have switched to a mostly generic art style for every. single. book. in the series. The prequel is green, books 1-11 have non-metallic colouring for the titles and series 'stamp', and finally 12-14, the ones completed by Brandon Sanderson, will or do have metallic colouring. Beyond that, they're all the same. I'll post the cover of The Eye of the World, which is the first book in the series in terms of publication.
As you can see, it's fairly plain. Every single book in the series shares the same style of cover, with the only difference really being the colouring. Looking at that, it tells me nothing about the series, nor the contents of the book. Is it a dark book, a happy run-around-and-smooch-Elves tale, is it set in modern times or in a typical fantasy setting? How am I to know, looking at that? Where's the hook, where's the eye catching part of the cover? On the back they all have a very thin strip showing part of a scene, but you can't see all that much. A bit of a horse or a person, mayhaps. It's pointless. That cover doesn't make me want to buy the book (The fact I have it is irrelevant), because it doesn't grab me. The only reason it stands out to most people who look for it is the amount of shelf space those books take up, and the fact it's Robert Jordan's Wheel of Time.
Let's look at Terry Brooks' The Tangle Box, which is a cover that I do like. This particular cover appears on some UK editions of the books, and also some US ones. Currently Orbit UK are publishing them in a more 'current' style of YA-esque cover, and I believe Del Rey are only publishing the omnibii now, but I could be wrong on that.
The cover was created by Keith Parkinson, one of the all-time greats of fantasy art, and I feel that it is highly evocative of the series. Here we see Willow, oddly wearing clothes (She spends the first two books at least walking around naked, although I'm not complaining as those trousers are a lovely fit), talking to another character, whom I don't know yet as I've not gotten to the book. But to me, it shows what the series is about. It's a lighter hearted, lighter toned fantasy read with a more traditional feel to it. That cover is attractive to me, and I have an edition of the book with that very artwork due to it. It tells me that I'm picking up a fantasy series, and that there are female characters in it who may very well be interesting to read about, rather than swooning penis-fodder.
I will buy a book used if it has a cover I like. I've done it for Elizabeth Moon's Vatta's War books, all of which I have in Del Rey editions, I'm doing it for Terry Brooks' Shannara universe of books and I will likely do it for the remainder of Tad Williams' Memory, Sorrow & Thorn. It's not so much that I want to screw the authors over, as I don't, but I think books are as much a piece of art on your shelf as they are something to engage yourself with. I love fantasy art, and I want my bookshelf to reflect that aspect of me.