But I can show you some sides in top ten positions that have Duplicate Content on different domains, work with doorways, redirects and keyword stuffing. That sides have not been affected to this "filter", instead they gained from the falling out of index from the white head "good" pages.
How does it fit into your idea of google having put up the spam defenitions?
Maybe they turned the switch into the wrong direction?
or they did a "not xnor" and canīt find it anymore.
There are to many errors that does not fit into a spam theory: Old pages in index. No new pages in index. To many good pages where hit. Bad pages obviously not...