I agree about the false positives with Penguin. I've had people look at my site, and they agree it's a false positive - for Penguin. The really odd thing is, I had just been waiting for the Panda hammer to fall on that site. When Panda first came around, I took a hard look and realized a lot of my pages were thin, and the site overall (despite a few very good pages) was weak. I deleted half the pages at that point and started rewriting all the rest - but it was slow going, because other sites were my priority now.
So when the traffic plummeted on April 24, I came in here expecting to see that Panda had put out another iteration. But no, it was this Penguin thing targeting webspam and SEO-boosted sites, and that's so not my site. If I'd been Pandalyzed, my reaction would've been, "Fair enough." But SEO/spam? If I knew how to use SEO to boost my sites, I'd have so much more traffic, LOL! It's laughable.
Either Penguin is very flawed or... I wonder if it interacted weirdly with the Panda refresh that happened days before. It's just so odd that my site should have gotten Pandalyzed but instead got Penguinized, so it makes me wonder if Penguin really behaved as expected. I mean, we know it produced some very screwy results by any objective measure (that "mold" thing).