I joined on a month-to-month plan in July, 2012. The gym is pretty good, no real complaints about the facility or staff. In September, they hit me with a $25 "enhancement fee" out of the blue. The claim from corporate billing was that this is in the contract. I don't remember anything about it, and I'm completely sure it was never pointed out by the guy that signed me up.
So, they get $25 and lose the $40 a month I was paying for membership. Good for them. I don't do business that way, and I won't do business with anyone who does if I can help it.