It's certainly not only Adsense sites, and it's most definitely not ALL Adsense sites. Still, what is the monetization strategy for low quality, mass-produced content? Adsense if they can get into the program, right? Otherwise, it's usually a second tier content network program that's similar.
So "Adsense Farm" is a reasonably accurate way to describe this kind of junk website. And they don't do Google any long-term good, either, even if there is some short term cash to be gained. I think Google is savvy enough to know that.
Please forgive me this moment, but I've just got to share a bit of satire from The Content Farm [thecontentfarm.tumblr.com]. This page just nails it - except it doesn't run Adsense ;)