I am faintly (very very faintly) amused that the advertising wonks think that tracking anyone as they browse the web will reveal their "hobbies and interests". Let's face the truth: advertising wonks are professional liars. They lie to the target of their b.s., they lie to the people who hire them, and they lie to themselves about the efficacy of their filthy tactics.
Offhand, I can't think of a single thing I've bought as a result of online advertising. Amazon does make "recommendations" based on my browsing of Amazon, and those have sometimes led to a purchase of music I wasn't previously aware of, but that's about it. And even Amazon isn't right a lot of the time. My purchases of a couple of small, sensitive scales (one good down to 1 mg, more or less) are related to weighing the cat's medication and nothing else, and I have no interest in buying another scale of any type.
It will be noted that weighing the cat's medication is not an interest or a hobby.
Adblock-Plus makes browsing almost entirely ad-free and much more pleasant (and useful) than when your browser screen is cluttered with silly, pointless, ignorant ads.
PS: The medication I refer to is KCl; kitty has a slight K deficiency.