I am signed up to be an affiliate with several sites, but I promote only the products I believe in and have personal experience with. The folks who make a great income (or say they do) seem to promote things that have good commissions, or that have contests attached, especially in the IM world. I prefer to not promote something I have not used. Does this limit my recommendations, and therefore my income? Sure. But when I do promote something, folks respect that recommendation.