I was at the Key Foods by my house and as I was standing in line the lady in front of me swiped her credit card on the little machine by the register about three times with no luck. Then the cashier handed her a plastic bag and told her to wrap the credit card in the plastic bag and swipe it. I kind of laughed to myself, but the lady did as instructed, swiped the bag covered card and it worked. I must have made a face because the cashier smiled at me, and I asked her “how did you figure that out?” and she just smiled.
Credit cards store their information on magnetic strips. That means that if this trick is more than just retail voodoo, it must be aligning the card in such a way to make it easier for the reader to scan it. Which, you know, doesn’t make a lot of sense to us.