diberry - 5:16 am on Oct 5, 2012 (gmt 0)
If there's one thing I've learned this years, it's that focusing on visitors and not on SEO will NOT cut it. That's what I was doing when one of my sites got Penguinized. A few people have looked at that site, and all the theories advanced about why it got hit had to do with things that were far from obvious to me - either as a webmaster or as a sensible and intelligent human being. (And not one person who looked at my site has mentioned backlinks as the problem - my link profile was hands-off from the start.)
I won't say Google is wrong if it Penguinized my site for the reasons suggested, but I will say that I've done my best to comply with the webmaster guidelines as I understood them while I focused on my visitors, and it wasn't good enough.