I have used the guarantee a few times and everytime had to insist they refund one nights stay,they just don"t come out and offer it most of the time.On one stay I had to call HH and let them know I would no longer be staying at any of their hotels, because of the quality problems at a property in SF.A few days later I had the hotel GM calling with an offer for a free nights stay.A few days after that I also got a gift card from HH for a free nights stay at any location I chose.So if the hotel does not honor the guarantee,a nice letter or call to HH will do the trick.I know first hand that hotels get fined if complaints make it to corprate, that should have been handeled by the hotel.