I think that usually these things are actually just a symptom of the fact we see hundreds of ads every day. Most of the time you don't consciously notice them b

I think that usually these things are actually just a symptom of the fact we see hundreds of ads every day. Most of the time you don't consciously notice them but then, when they trigger some recognition, you do and it feels like a big coincidence - which I find almost as disturbing as the idea that they were somehow watching. The eerie feeling compounded by the fact that we are sometimes correctly targeted and there's no way to distinguish the two. Zeynep Tufekci writes a lot about the this type of thing if you're interested in it.