Need honest opinion on promoting clickbank products?

Has anyone ever promoted clickbank products and made a little money? The reason I ask is because I was thinking about signing up as an affiliate. I am pionate about Alzheimer's. There are a few really good ebooks on this subject, but would this be impossible to promote? I'm not expecting to get rich, but maybe a few hundred dollars extra would be nice. I've read a lot of mixed reviews about clickbank. Some say it was just a huge waste of time, others say they really like it. I have heard that when you do sign up with them, you need to get a domain name in order to cloak you clickbank link. Why? I would really appreciate an honest opinion. Would this be worth trying?