Technically, this is against most merchant agreements anyway. I've often wanted to create an "I have to adhere to my credit card contract and so do you" tearsh

Technically, this is against most merchant agreements anyway. I've often wanted to create an "I have to adhere to my credit card contract and so do you" tearsheet to hand out to merchants who require insane minimums (like bars and their $10-$20 minimums) and require ID for verification.