Barence writes "PC Pro has a feature on how social networks sold your privacy, which includes some interesting comparisons on the value of different demographics to Facebook. For example, an advert that targets everyone within a 10-mile radius of a medium-sized British town (Dorking) is valued at 28p per click by Facebook's advertising tool. However, targeting single gay men in the area with a preference for nightclubbing raises the price to 71p per click — 2.5x the price of targeting the general public. Such precise targeting also raises other issues. Whittling down ads to target such precise demographics can result in ads targeting as few as 20 people, making it theoretically possible to identify those targeted. 'I think the worst scenario might be where someone who hates gays uses Facebook's targeting to identify gay users and later attack them,' says Paul Francis, scientific director of the Max Planck Institute for Software Systems."