Thanks Content_ed - interesting.
I have one of those sites on your list. I've pretty much applied all 4 of Tedsters things that were fixed on other sites. And, as your list shows... no change. The amount of time that has gone has been huge (many hundreds of hours).
Scraper issues are almost impossible to keep on top of. I've done some very drastic things to the site, but as yet nothing.
One thing I am struggling with is that all referrals from Google seem to be for very long tail keywords, making it much harder to lower bounce. Pre-panda many pages ranked for much "bigger" keywords - making the content of the page more aligned with what the searcher was looking for.
Thanks again for all research. It all helps.