The gout example in the article strikes me as very odd, since the only site that should've received the referrer with the search terms was wikipedia. Therefore

The gout example in the article strikes me as very odd, since the only site that should've received the referrer with the search terms was wikipedia. Therefore we've left to conclude that either Google is targeting ads in their AdSense network based on search terms (which is outside the scope of Gabriel's argument) or Wikipedia is passing search terms to ad networks that for some reason it doesn't display ads from. Equally likely is that this concerned user clicked on a different health-related site with an ad network that classified him according to that site's content or stated category -- there's simply no evidence that the aggregation of search terms happened. Note: I'm not saying the story couldn't be true, just pointing out that no technical evidence has been presented to rule out the other possibilities.