I used a "bad" card inadvertently one time for a prepaid Hyatt stay. I transposed two digits in the card number and the hotel could not bill me. Surprisingly, no one contacted me, but my reservation was intact despite arriving after 11 p.m. I just had to pay for the entire room and tax (at the special prepaid rate) upon checkout.

I'd never do this deliberately, though, as I wouldn't want the hotel to send me a bill out of the blue for a no-show.