After reading an article about ad metrics I realized this is ad fraud.
What is going on is a business buys ads and pays one rate for ads shown but pays a higher rate if the ads resulted in a conversion (a sale). But the ad contracts are monthly or longer. So a business buys ads for their product and the ad company after noticing you bought it, stuffs your feeds with ads for what you just bought so they can bill those ads at the higher conversion rate.