My new rule of thumb post-Panda is if the content isn't long enough to be an article, it's too risky to get indexed by Google. I noindex, no follow all new content on short pages.
If you have a bad but "authoritative" site (tricked Google), it's like the mafia. You can pay off the police and judges (Google) to ignore your weak page crimes for which everybody else gets booked and jailed.
I've seen pages on these "authoritative" sites barely long enough to fill a post-it note jump to the top in rankings post-Panda. Pandas have never been called the most intelligent animals on earth.