As my tastes in literature have changed I've noticed that I go less and less for cool looking covers and cheesy fantasy novels to more and more realistic fantasy novels. Not realistic as in the fantasy being gone, but realistic as in feeling like the characters could be real people. What really makes me disgusted reading a novel, any novel, is the author playing God with the characters. Machina Ex Deus is lazy writing and a sign that the author is not serious about the humanness of the characters. And if we aren't reading novels to explore humanness at some level, what is the point? The characters are what drives Game of Thrones for example. These feel like real people put into real situations acting in a real way.
Another thing that turns me off of books is not getting to the point. The Wheel of Time is a great example of this. It started off great, neat world, real characters, high fantasy stuff. Then it kept going and going and going, with nothing being accomplished and whatever the characters did accomplish would seem to be set back with convenient resurrections and new prophecies. This was never going to end. I want my time back.
The above things that pull me into and push me away from a book are hard to quantify just by the dust jacket. I usually only go for books recommended to me by the serious readers that I know in my life. I usually can't stand the copy that is put onto the dust jacket. This is why there are things like GoodReads, and Reddit, and the good ole' fashioned book club.
Brett Lindskog is a good friend of Christopher Patterson and an avid fantasy and science fiction reader as well as a reader of Christian motivational non-fiction.