Do you have one of those supermarket loyalty cards that you swipe to get a fuel discount?
Well, there's a story in the Sunday Age that has just confirmed what I've suspected (known) for some time. Those organisations use those cards to keep tabs on our buying habits.
Every time you swipe your loyalty card a little bit of you is gobbled up by the Supermarket. It not only tells them what you're buying, it also allows them to compile a profile on you so thay can then specifically market their goods to you.
That's why I never use one of those cards. The less info they have about me and my buying habits, the better.