I know we have all seen it - in theory, at least. Too many people sign without reading. But this snippet sums it all up. And it's not even from one of the "bad" HMOs:

Payment Policies
Payments for covered services under this agreement are subject to the payment policies. Those policies may change from time to time. HMO will make information available about Payment Policies upon request or at a website identified by HMO.

I think it would be more clear if it read:

We can change the rules whenever we want and we don't have to tell you.

At least that would be honest. Fortunately, there's now a solution.