Some sites cannot do any wrong in Google's Panda eyes. I have seen a ONE line contest link outrank the site that was actually hosting the contest. Like me having an entire page with "Webmaster World is having a $10K contest on coding" wrapped with my templates and ranking #1 for the query.
Or a single tweet showing #1 for a major news story in a site that was unloaded to AOL last month. ONE TWEET and gazillions line of template and code. How's that for thin, but Panda loves it. Almost as much as it loves bamboo shoots :)