It seems to me that most hotels have rather liberal cancellation policies - usually 4-6pm the day of the reservation. That seems fair to me, after all they make their money based on people sleeping in their rooms. Now if you frequent the hotel often then I would think that they would accomodate you for a special circumstance, but otherwise I'd expect that they would charge you.

And lets face it, many people are "less than honest" when claiming special circumstances.