Just as a data point, I have twice forgot to cancel reservations I made and failed to show up (once at the Westin Pasadena and once at a non-Starwood hotel in Colorado Springs (possibly a Wyndham)).
In both cases I called and apologized profusely and they both reversed the fee. I guess it will always be a case-by-case basis but if you're wrong it's probably best to own up to it and and beg for forgiveness.
