I don't know about you, but that's completely unacceptable to me.
Don't despair, you can stop it from happening by reading Thorin's article on LifeHacker.
As we mentioned, the way this data collection works is that it compares your online data with offline shopping habits. So, the easiest solution to keep it from happening? Don't use the same phone number or email address on your Facebook account as you do when you sign up for loyalty or discount cards. -Thorin Klosowski