AOL's Smart Money goes into great detail about the dirty little secrets that Fitness Clubs don't alert you to about the risks of joining a gym. It covers everything from unsafe and unsanitary equipment to theft and liability waivers.
I've joined a few gyms in my time. Most were very clean with staff that were somewhat knowledgeable. But managers tended to be pushy on selling their goods and services... I was constantly nagged to buy protein bars, shakes and the like... It usually ended in me quitting the gym. I never even thought about getting a bacterial infection, or having my stuff stolen..