I've noticed that most of the sites that 'affiliate' are either: A) Really umm... "new" websites, usually made by those new to making websites as a whole... who are just affiliating to anything and everything they have the vaguest interest in, that will affiliate back. or B) People with sites that have like... 50 affiliations on the homepage, which just tend to be a link-site with very little content. Just basically a personal 'favourite links' page. or C) People affiliating with sites made by close friends.
It's rare to find a site that's not one of the above. Most others just have links pages in general, such as myself. And that's not so much affiliate, since I tend to not care if they link back to me or not.