The quick and dirty answer for those of you on the run is false. I did a complete report (working with law enforcement) on the question less than two years ago. Here now are bits and pieces of the story for those who have the time and interest to learn more.
Modern-day hotels (including resort-casinos) are increasingly using credit card-type "key cards," as opposed to old, bulky, metal keys, for opening their hotel-room doors. Overall, the plastic keys increase security for guests. Metal keys can be duplicated and most old-style keys had the room number engraved on one side of the key and the name of the hotel on the other. Thus, the old keys not only tempted someone to commit a criminal act, they also gave directions. Key cards don’t advertise the room number in any way.
As for the magnetic strip on the back, this is programmed upon check-in with the following information: dates of check-in date and check-out. That’s all. Nothing more. The key becomes useless after the programmed check-out date; it self-expires, after which it cannot open the door.
So if check-out time is 11 a.m. and you go out and come back at noon, don't be surprised if your key doesn't work. Tick-tock-lock. If you call the desk and ask for an extended check-out time, you'll usually get a few hours grace (unless a it's a Friday or holiday) at no extra charge. If you accidentally leave your camera, glasses, blow dryer, or poodle, etc., you can contact the front desk and someone (usually a security supervisor in a casino) will show up to grant you access.
This report surveyed numerous major hotel-resorts and casinos in Las Vegas, Reno, California, and Florida, as well as several major computer companies that either produced or used key-card technology, and the conclusion was the same for all regions and sectors: No key cards contained any personal information on them. This even includes the guest’s name.
You might ask, "Then how am I able to charge things to my room?" If so, you just answered your own question: You charged it to a room and, contrary to the urban myth, not to your name.
That said, never lose your card. If you do, while it’s still active, anyone who finds it could conceivably go on a shopping spree at the hotel, billing all goods (usually booze) and services (usually food) to your room. If you lose your card, contact the front desk ASAP to kill your key card and have a new one programmed for your room. If you’re too late and the card has already been used to purchase alcohol, don’t hesitate to dispute any extra charges. In such a case, especially in a casino, surveillance will be your savior. The second-most watched commodity in a hotel-casino is alcohol; the surveillance cameras are always watching.
One of the members of the study cited a police case where investigators broke up a group of credit-card crooks. They had a ton of stolen key cards from several hotels. The police scanned them to obtain the information off the magnetic strips, only to find ...nothing. They later learned of a tool this fraud ring was using to program the hotel key cards with credit- and debit-card numbers. Crooks can use such a credit-card scanning device to steal credit- and debit-card information, program it on to a hotel key card and use it like the real McCoy. But this is true for any card with a magnetic data strip.
Here’s a secret for all key-card users. A member of the hotel staff has the ability to do an "entry audit" on your door. This means if you think someone went into your room and took your watch, money, poodle, girlfriend etc., they can audit the lock to see up to the last 20 entries. This is useful, because each housekeeper on each floor has a limited 1201 (master pass) key and it’s easy to figure out if the maid made an unauthorized entry into your room. If so, security looks at the employee schedule to see who was working that shift and at the time of the entry. Maids’ and porters’ keys must be returned to
