Is smoking in a non-smoking room considered damage to a room?
From the MasterCard Chargeback Manual, April 2010:
2.1.9 Charges for Loss, Theft, or Damage
A charge for loss, theft, or damage must be processed as a separate transaction from the underlying rental, lodging, or similar transaction. The cardholder must authorize the charge after being informed of the loss, theft, or damage.
From the Visa Hotel Merchant Procedures, 2004:
After the guest checks out
• You may deposit a separate sales draft for delayed charges, with the words “Signature on File” on the signature panel of the sales draft.
Note: You should only do so if the guest has agreed to be responsible for such charges. You may not submit a separate or amended sales draft for loss, theft or damage to the room.
So with MasterCard, unless a hotel first informs you that they will be charging you and you agree to the charge , any charges claimed by the hotel for loss or damage due to smoking should be possible to reverse as unauthorized.