Wal-Mart knows you and they are going to get you!
Just kidding of course, but this is a very interesting article about how much Wal-Mart knows about its different customers. I remember a direct feedback loop I heard about one time, where Wal-Mart was able to change the packaging of a certain type of Roach and Ant spray because in certain sections of the country it was socially unfavorable (like the outline of the ant was on the package or some such). I love data mining... all the answers are right there, it's up to you to dig it out. Of course, the hard part is understanding what is causation and what is causality.