It's like me using an FBI fax number with merchants...it's still stored in the Best Buy database!
Remember when Radio Shack used to ask for address info etc. even when paying cash?
Yes. When I asked the guy why he wanted it, he told me it was in case I needed to return something and I lost my receipt. I snorted at the guy and told him I don't lose my receipts, he wasn't getting my info, I didn't want to be in his damn computer and was he gonna sell me the doodad or not?
Just tell them no, all of them. If they want to know your zipcode, ask 'em 'what's the zipcode for the store? Put that in.'
Of late, the restaurants, instead of handing out pager/buzzers when there was a waiting line, they'd want your cell number. Bullsh it to that, give me one of the few buzzers you do have or I'll go elsewhere.
Tell them nothing. They turn around and sell your information. They get paid and you get pestered.