netmeg - 8:50 pm on Mar 3, 2011 (gmt 0)
It can't be just the presence of AdSense. None of my AdSense sites were hit. They don't earn on the scale of a content farm, of course, but still. I still see plenty of other sites with AdSense out there, of varying quality (in my admittedly subjective view).
Now, placement and amount of AdSense in relation to content might be a factor. But it's not just the fact that there's AdSense.