Let’s just say that all the people wetting their pants about the intrusiveness of targeted ads can probably relax for another ten years or so, because the Google algorithms, amazing as they are in many ways, are in some respects just the 21st Century equivalent of Hans the Clever Math Horse. Occasionally the magic trick gets caught in the act and it becomes clear just how far it is from anything like an intelligent agent.
For example, downloading a .pdf of a chapter of Elliot J. Gorn‘s The Manly Art: Bare-Knuckle Prize-Fighting in America so that I can put it into Blackboard for my seminar, I get three ads for Star Trek stuff and one ad for Enterprise car rental.