Originally Posted by deltabound

Here's one SCAM that unscrupulous flight attendants have been known to run (or so I've heard):

If they can accept both cash and credit for in flight purchases, they can effectively "double dip" by doing the following: They run your credit card once for an item purchase, then later run it again a second time without your immediate knowledge. They then take the second charge out of the "cash" till, pocket it, and hope no one notices or contests the second charge. It's fairly easy to do, because inventory control on airplane items is pretty sloppy (for food and beverages especially) and mostly left up to the integrity of the flight crews.

I heard about someone catching this scam on an international flight where they were double charged for an expensive item (duty free stuff), which eventually led to the culprit being discovered and terminated.

Now only .000001% of flight attendants would be dishonest (and stupid) enough to try this. That said, for a small amount, some might just be counting on you not bothering to contest it because of the hassle.

One of the many reasons airlines are moving to the "credit only" for inflight purchases.