Try the experiment with friends!
First, get a friend or relative to go along with the ride here. Try to have that person not be on your local network of wifi and the like.
Then, go a website that will generate a list of random words: https://www.randomlists.com/nouns . Make sure that you are selecting for nouns or adjectives. Copy the first three words that you get. More is fine too. Just get enough words to be pretty specific.
Then go to amazon or some such online retailer: https://www.amazon.com/ . Search for the three random words you got.
Now, here is an important step, sort the returned list by price, from high to low.
Take the most expensive item as your experimental item. You can do this with a few items if you'd like. You're just trying to get something that is not what you or your demographic would normally look to purchase.
Then, talk about that item around your gadgets, critically, with someone that is not you. Your amazon search history is already corrupted just by searching for this.
Check back in with your friend or relative in about a week. You can set a reminder in your phone to do this. See if they got any ads that were trying to sell them on the random item you chose.