Call me a cynic, but I think this is a certain level of anti-affiliate, anti gaming, anti adult sentiment at Google that parallels what we see at DMOZ. As a result I think that they are less then motivated to devote resources to this particular area.
They have already stated they do not WANT online gaming advertisers (I know a few people sneak in under the radar). I think that in itself indicates they aren’t too interested in cleaning up these categories. They just might be of the opinion “Hey let these scummy affiliates kill each other. We would be better off devoting our engineering resources to developing new mainstream products that will increase our bottom lines and market value”
I dont think they really care much about this (I know WE do, but they dont) and arent going to spend thousands of programming hours trying to put “good affiliates” back on top of their serps.
I am sure if they had their druthers all affiliates, good and bad, would be eliminated from their search directory and that only lilly white information publishers would appear in the serps.