I have a dozen online identities, and no matter which one I used or where I logged from, I saw an ad for the same book.
Something similar happens to many in the CIA. There is talk of a mole flagging us, but I think _it_ just got too smart for our covers. It's not aware, it just profiles people and shows ads.
The ads I see are changing. It's plane tickets now, and to very specific places, too. I know it's just advertising, there's nobody trying to intimidate us.
It doesn't help much.