You have heard the warning. Somebody forwarded it to you, or a relative mentioned it, or you saw it on a screen in an airport.
Do not leave your hotel key card behind. It has your credit card number on it. Thieves collect them from the bins by the elevator.
Gif by imaginedragons on Giphy
It has circulated for roughly thirty years. It gets reposted every few months. Police departments have occasionally repeated it.
It is false.
Not exaggerated. Not mostly false. Flatly, comprehensively false, and researchers have tested it by reading the cards directly. What they found was room numbers and dates, not payment data.
But here is why this article is worth your time anyway.
The thing people are afraid of is not real. The thing they are not afraid of very much is.
Because hotel locks have had genuine, serious, documented security failures. Real ones. Vulnerabilities that let people open doors they had no right to open, at scale, across millions of rooms.