gouri - 6:44 pm on Jul 7, 2012 (gmt 0)
We can think of Penguin as demoting pages that were mostly ranking because of SEO efforts rather than their inherent value. I think Penguin looked for both positive and negative signals and then mixed them up into a single "Complex Cocktail".
Your second point, which I think is a great one, made me wonder if a website has good content and it is also over optimized, is the over optimization looked at more? Would a couple of areas of over optimization make Google say the content is good, but it is over optimized?