A reason Amazon search may suck: authors are filling amazon with crap content. I listened to a youtube video that said their model to make money on amazon was to produce a children's book a week. Which is possible given current tools and ebook publishing. So you make a little money on each book but you make it up in volume.
This is not unlike the blog publishing strategies of frequent content updates to get more page views. Well, this is essentially a DDoS attack on the search algorithm. Which may be why Amazon search sucks. - Todd Hoff