Another thing I see a lot is scammers scraping my blog's RSS feed and re-publishing my articles on their site, then filling it with adware. Sometimes the page they show to googlebot is completely unrelated to the page you get when clicking through.
Have you had any luck getting them to take that content down?
In my experience, Google's dupe content detection is pretty good and their penalty is harsh. I once ran a website that tried to curate and touch up old usenet material that never could rank all that well because of dupe content (another website had monospaced dumps of the usenet content).