That's why you should not keep checks with purchases

I work in an expensive boutique. We sell designer clothes and shoes. We have regular customers. And one of the weekdays one of our regular clients came to us. She was accompanied by a girl (by behavior one could conclude that they are good friends).

Our client chose clothes, paid for the goods and left. After a couple of days, the client returned the goods. The sellers checked the condition of the goods, the presence of checks and tags. The goods were returned to the trading floor.