You arrive at your hotel and check in at the front desk.
Typically when checking in, you give the front desk your credit card (for any charges to your room).
You go to your room and settle in. All is good.
The hotel receives a call and the caller asks for (as an example) room 620 - which happens to be your room.
The phone rings in your room. You answer and the person on the other end says the following:
'This is the front desk. When checking in, we came across a problem with your charge card information. Please re-read me your credit card numbers and verify the last 3 digits numbers at the reverse side of your charge card.'
Not thinking anything wrong, since the call seems to come from the front desk you oblige.
But actually, it is a scam by someone calling from outside the hotel.
They have asked for a random room number, then ask you for your credit card and address information.
They sound so professional, that you think you are talking to the front desk.
If you ever encounter this scenario on your travels, tell the caller that you will be down to the front desk to clear up any problems.
Then, go to the front desk or call directly and ask if there was a problem. If there was none, inform the manager of the hotel that someone tried to scam you of your credit card information, acting like a front desk employee.