But they track you across devices. Did you ever search on another device? Have you ever hovered your pointer over the image or listing on an online store? Have you ever shown interest in that product on your device? There’s so much more to it, but the main thing is priming. If you’re already the paranoid type and I say "ever notice how many blue cars are following you and most of the drivers are government agents?" then it’s likely that you'll suddenly start to take note of blue cars, and possibly believe the occupants are after you.
There’s an easy solve to this: don’t use Facebook.
