You know the ads that are targeted to you on websites? Sometimes I'll look at a yarn store, and then I'll get an ad for Webs. I've gotten ads for the world's most powerful commercially available laser, and for motorcycle pants. But the most frequent ad I get is for Zulily's "clothes for every size".
I have nothing against clothes for every size. But, the only clothes I've ever bought online were a small t-shirt and a whole bunch of shoes, so I have no idea that Google AdSense or whoever decided I'm the target audience for that ad.
It makes me sad.