You'd think advertisers would have learned by now how to avoid embarassing themselves. Clearly, they have not. Every year there are advertisements that fail to account for cultural values, context, or placement, and wind up sending an unintended message. Sometimes it's hilarious, sometimes its tragic. You've all seen the jars of Gerber baby food, right? The one with the big baby face on the front? Turns out when they first tried to sell it in rural segments of Africa, it wouldn't sell -- like at all. Turns out that the majority of the population in those markets is illiterate and so the products contained pictures of what was inside the jars and boxes. Well, the locals thought Gerber was selling, achem... baby. Needless to say, the packaging was updated shortly thereafter.
Here's the problem with advertisements where people are aware they are being targetted: What if the machine makes a mistake? What if it identifies the 18 year old male who's captain of the football team with a couple of his female friends and the machine decides that there are three females in the party instead of two, and spits out an advertisement for tampons or makeup. Perhaps even doing an impromptu photoshop with their faces and a "before and after" shot, with directions to the nearest makeup counter? Well, he might need some coverup then... To hide his suddenly very flushed appearance.
The problem with mechanical identification of any physical trait in a human being is that it won't ever be 100%, because the meanings associated with those traits are context-dependent. That is to say, the correlations are the problem, and it's true whether it's a matter of sex, race, or age... And when people are aware they are being targeted by those factors, and especially when its misread, and very especially when others are aware of this -- it can have significant social reprecussions. In marketing, context and placement means a lot -- and the only thing saving people from taking it personally is the very fact that they know it's targeted impersonally. When that changes, marketers are going to be in for a real surprise.