[basch]

does google sell data or attention? the whole point of google/facebook ad networks is that THEY keep the data hidden and let you use it as a filter, without being able to see it. they would lose their value if their data was for sale.

google would sell "attention time to people whos heart rate spiked during the world series" but not tell the customers who those people were. you would be outing yourself if you click the ad.