crobb305 - 4:29 am on May 1, 2011 (gmt 0)

Google says they do not have an 'over-optimization' penalty (5), per se, but that could possibly be translated to 'a bit on the spammy side'

Exactly. They have phrase-based document scoring in place (I see it in action on my site right now for one of my phrases). Per their patent, a document could be labeled as "spam" when phrases exist outside of the "expected" probability distribution. [seobythesea.com...]

"a spam document will have an excessive number of related phrases, for example on the order of between 100 and 1000 related phrases. Thus, the present invention takes advantage of this discovery by identifying as spam documents those documents that have a statistically significant deviation in the number of related phrases relative to an expected number of related phrases for documents in the document collection."

_{Note that there is a big difference between labeling a document as "spam" versus not ranking well. Phrase-based document scoring might trigger a ranking reduction for a phrase (again, when occurring more/less than expected); then, at some point, it could peg the whole document as spam and you get spanked.}