After arriving at your destination you check in at the front desk. When checking in you give the front desk clerk your credit card for all related charges. You get to your room and you are relaxing.
Someone calls the front desk and asks for your room number. The front desk transfers the call to your room and when the phone rings you answer. The person on the other end says, “this is the front desk, after you checked in we came across a problem with your credit card information. Please re-read your credit card number and verify the last 3 digits on the reverse side of your credit card.”
Perhaps not thinking clearly due to your travels, you might give this person your information since the call seems as though it is coming from the front desk. Later you learn it is a scam from someone calling from outside the hotel (or perhaps a criminally inclined employee). They ask for a random room number, then ask you for your credit card information. Sounding like a professional staff member, they convince you that you are talking to someone at the front desk.
If you ever encounter this situation on your vacation, tell the caller that you are coming down to the front desk to clear up any issue. Once you get to the front desk, verify if there has actually been a problem with your credit card information.
This scam highlights the strategy of never providing your personal information except to reliable and confirmed sources. These should be sources you have dealt with previously, or where you have initiated the contact. Reputable businesses do not call and have you provide your information again, especially online or on the telephone. Be suspicious of these requests and always verify you are dealing with a legitimate entity.