[ale] [OT] Weird Trick to make Debit Card Scan

[tfreeman at intel.digichem.net (Tom Freeman)]

Ok. WAY way off topic for here I know, but this is about the only place  
I know of where there are people who _might_ be able to guess an answer.

I was shopping this evening, and as is becoming common, my debit card  
didn't want to read when I passed it throught the little device by the  
register. The cashier grabbed a plastic bag for bagging purchases with,  
and told me to put the card into that, and try again. Worked like a  
champ. I don't really want to look a gift horse in the mouth (I don't  
want to look in a horse's mouth at all), but does anybody here have an  
idea _why_ the bag trick worked? Frankly I'm stumped.

Thanks in advance