Here's what I ALWAYS do when using a card. when they give you the slip to sign, find the CC # and ink out the last 4 digits AND the exp date. BOTH SIDES OF THE SLIP.. i ink the toejam out of it to the point the paper is ripped., F em.
sometimes the slip has an XXXX XXXX XXXX 1234 for the cc #.. I still X out the last 4. once the transaction is done THEY DONT NEED THE CC NUMBER ANY MORE in fact, if there is a problem there is always a reference number on the slip they can refer to.
I get dirty looks from the empty headed cashiers.. screw them too.. I work in the industry.. you know where the old slips go? into the trash can in the alley.. you can't stop people from stealing #s.. but you can keep them from getting YOURS.
ok.. rant mode off:p