On its surface, this partnership between Facebook and the news/commentary site Politico sounds like a good idea.
Facebook Gives Politico Deep Access to Users’ Political Sentiments
[T]he Facebook-Politico data set will include Facebook users’ private status messages and comments. While that may alarm some people, Facebook and Politico say the entire process is automated and no Facebook employees read the posts.
Rather, every post and comment — both public and private — by a U.S. user that mentions a presidential candidate’s name will be fed through a sentiment analysis tool that spits out anonymized measures of the general U.S. Facebook population.
I’m actually not all that worried by the privacy issues. I am more concerned that this is crappy data, easily gamed. Let some well-funded Astroturf organization create thousands of phony personas all trading private status messages with one another about how they love candidate A or staunchly oppose issue X, and watch as the numbers creep up.
Seriously, statistically valid polling is hard work. Facebook data mining is no substitute.
Ed Bott (@ wordpress.com) 
Not just gamed, but I wouldn’t put it past a lot of people (and rightfully so!) to just start posting political names just to screw up the database, in protest.