I think the truth is actually that we are MUCH less unique than we would like to believe, and that some combination of age + gender + location probably predicts like 80% of our interests.

> This is called observational bias.

I think you mean confirmation bias. Observer bias is similar, but relates to being non-blinded during a scientific study.

This is especially blatant when you don't fit into any category advertisers understand. Most of them think I'm either a hip urban youth or a well-off exurban housewife. I don't think they know what to do with someone who has associations, friendships, and interests that cross countless geographic and socioeconomic boundaries.