BeeDeeDubbleU - 6:40 am on Sep 26, 2012 (gmt 0)
In my experience it is more about over optimisation than spam.
Think of Penguin as being more about spam.
Once again [in my experience] you are correct. I had three sites that were badly hit by Penguin on 24 April. Spam was not a problem on them and AFAIK the optimisation was all within Google's guidelines. It may have been a little overdone; every opportunity to score algo points was used but it was within the guidelines and I don't think that established sites like this should have been hit as badly.
I may seem to be off-topic however it is important to understand that whilst trying to comprehend Penguin that one must realise that Google had no idea what it was unleashing on the "regular" websites whilst "supposedly" targeting the manipulators, hence the all round crazy collateral damage.