Google said two things on the bannings, "we dont like thin affiliates and spam/scam stuff". Like google money tree, teeth whitening cures, acai products endorsed by CNN and all that stuff. IMO most eBooks fall into that, hyped up sales and squeeze pages with in most cases a poor quality product. Be it fake acai pills or plain bull$h!t eBook content. If you are selling e-products via sales or squeeze page methods i would change, g doesnt like them.