Reliable in what sense?
Cuz I find that a little hard to believe since I use a fingerprint scanner at my gym (a 24 Hour Fitness in Riverside County) to check in every day.
How it works is I punch my phone number into one of about 4 keypads at the front counter and then hold my forefinger over the scanner next to the keypad for about 10 seconds. When the light turns green, I enter the gym.
BTW, I've had no issues using the fingerprint scanner for entry at either the Eastvale or Irvine 24 Fitness gyms either.
I doubt anyone would be interested in fooling or tricking your gym's fingerprint scanner. At best, you'll eventually start getting FAR (False acceptance rate) and FRR (False rejection rate) with the less expensive scanners. At worst:
"But, as effective as they are, they certainly aren't infallible, and they do have major disadvantages. Optical scanners can't always distinguish between a picture of a finger and the finger itself, and capacitive scanners can sometimes be fooled by a mold of a person's finger. If somebody did gain access to an authorized user's prints, the person could trick the scanner. In a worst-case scenario, a criminal could even cut off somebody's finger to get past a scanner security system. Some scanners have additional pulse and heat sensors to verify that the finger is alive, rather than a mold or dismembered digit, but even these systems can be fooled by a gelatin print mold over a real finger. (This site explains various ways somebody might trick a scanner.)
To make these security systems more reliable, it's a good idea to combine the biometric analysis with a conventional means of identification, such as a password (in the same way an ATM requires a bank card and a PIN code).
The real problem with biometric security systems is the extent of the damage when somebody does manage to steal the identity information. If you lose your credit card or accidentally tell somebody your secret PIN number, you can always get a new card or change your code. But if somebody steals your fingerprints, you're pretty much out of luck for the rest of your life. You wouldn't be able to use your prints as a form of identification until you were absolutely sure all copies had been destroyed. There's no way to get new prints.
But even with this significant drawback, fingerprint scanners and biometric systems are an excellent means of identification. In the future, they'll most likely become an integral part of most peoples' everyday life, just like keys, ATM cards and passwords are today."
http://computer.howstuffworks.com/fingerprint-scanner5.htm
