The deception can be spotted instantly by plugging into the credit-card company's computer. For all practical purposes, the only way to come up with a genuine credit-card number is to read it off a credit card. The number, not a piece of plastic is enough. You might be thinking that you could just write the cardholder's name on the panel. You're thinking that this would be great if you were going to withdraw some cash from the bank, for they make you sign a slip and it must match up to the signature on the card.
Some credit cards have background design that rubs off if anyone tries to erase the signature.
The principle is the same as with the security paper, the wavy-line pattern erases, leaving a white area. This makes it obvious that the signature has been altered. There is a more elaborate gimmick in credit-card panels. The Administration has taken 15 common credit cards and sacrificed them to test this theory. The odinary pen eraser will erase credit-card signature panels, if slowly.