deadsea - 12:16 pm on Dec 19, 2011 (gmt 0)
Do you think these are factors that Google is measuring directly? It seems to me that pages with no rich media, auto-generated text, and ads in prime real estate could all be detected using user experience metrics (long click detection). It may not be they are measuring ad placement, but measuring visitors' reactions to overwhelming ad placement.
I'd think they must have written some algorithms to detect re-written content. I don't think that could have been detected algorithmically. If I were asked to write such an algorithm, I can't imagine how I would start doing so though.