Thank you for the insight guys. I though there was something fishy about why I haven't seen gambling affiliates promote books, but now I understand.
But, even though the commission is not worthwhile our effort, what about the visual effect with the visitors? Don't you think they might see it as an interesting feature of the website he is visiting and think of it "a bit highly and more relevant"?

)))
I am aware that gamblers wouldn't bother buying books about gambling since there are lots of resources on the Internet, and providing them quality content is enough to leave a good impression in them, but even so...