These articles on The Hustle can you give a new kind of perspective.

http://thehustle.co/underground-world-of-kindle-ebooks
http://thehustle.co/part-2-confessions-from-the-scammy-underground-world-of-kindle-ebooks
http://thehustle.co/part-3-confessions-from-the-scammy-underground-world-of-kindle-ebooks

Hope it gives you a few pointers in the right direction!

P.S. I, in no way, condone some of the black-hat techniques mentioned there.