Here's a link to a story about how business "gets to know" you and how they can use what they know. It's kind of scary in a way. It's a long read, but something everybody should be aware of. How Companies Learn Your Secrets I had figured that the grocery stores used the data they got when you use their discount card at the checkout, and that they would eventually sell the data (like to medical insurance companies so they'd know how healthy or unhealthy your diet was so they could adjust your premiums accordingly). But this takes data and marketing to a new level.