Why does putting your credit card in plastic bag for scanning help the scanner read a worn-out card?

At the grocery store, my credit card doesn't always go through right away when the clerk scans it so often they put it in a plastic bag and scan it and voila, it usually scans right away. Wondering why this would help a scanner read a worn-out card with a magnetic strip that is getting old.|||It puts extra material in the area of the scanner with the "READ" head which is set for the thickness of a "normal" card


If your card is worn this then forces the card against the "READ" head harder there by transferring the information to the "READ" head and to the computer.|||http://cr4.globalspec.com/thread/2432/Pl鈥?/a>





http://www.popsci.com/article/2007-11/cu鈥?/a>