I bought a specific airfilter from home depot once (prob 15 years ago). 6 months later I went back because I needed a filter. I couldn't remember which one I bought so I popped on their website, from my phone. I found the unit I bought and got the filter that it needed from the store.

For the next 3 weeks straight, every other add on every page, on facebook, on amazon, on everywhere was the air cleaner I purchased. They must have spent at least $5 on me alone it was the only static ad I saw the entire time.