Thanks, very interesting.

But a mixed bag:

• Pretty accurate: age, sex, education level, interest in music.

• I may understand why they think so: Interest in "construction and power tools"? Well, I bought an electric drill last year and searched for reviews and comparisons. But that drill will probably last me a decade or three, it's not like an ongoing major interest. Interest in "east asian music", is that because I watched the Gangnam Style video on Youtube?

• I've no clue where they got that idea: Interest in boating? Really? I don't live by the sea, don't go boating, can't recall ever doing a boating-related search. Interest in soccer? Nope, never been interested in sports.

I assume Google has more accurate details that they are not sharing out of worry of scaring us off. But if this is what they are selling to advertisers, it's a bit of a crapshot.