Black stains on top of the foil card = Card cannot be used anymore ?

This is a sms shared by one of the card seller regards her selling experience with another of her customer :

"Customer suppose to order 2 scorches..but he end up purchase 1 scorch only...cos he check the other one got few black spot at the edge and he end up purchase 1 only. He scared cannot play...even i told him that its ok cos so far i play its no problem..."
~ Seller 8xxxx627 who had also quit AK