When I consider targeted advertising and the sheer amount of data that I've pumped into Google services over the years it's scary to see how accurate of a picture advertisers and co have of me.
Why does this scare you though? I am curious as to why people are so afraid of advertisers seeing their interests. Personally, I don't care if I get served targeted ads, is that really going to harm me?
I use google extensively, gmail for years, google docs, etc. I must have clicked the right things in the privacy checkboxes since when I go to that "what does google think of you" page, it just says it "does not have enough data".
Save your opt-out preference permanently http://www.google.com/ads/preferences/html/intl/en/plugin/
Ads Preferences Manager http://www.google.com/ads/preferences/?hl=en
Google Advertising and Privacy http://www.google.com/privacy/ads/