This is a great thread. It has given me much to ponder. Here are some of my thoughts on the subject. I'm looking forward to reading your responses.
Using a code which we did not contract for increases the bargaining power of the company whose code we are using and reduces the bargaining power of the hotel, resulting in a quantifiable loss of revenue for the hotel. Loss of revenue for hotels adversely affects the pay of those who work there, the level of service other guests receive at the property, and maintenance levels/the rate of property renovation.
Hotel management companies have carefully calculated the cost of having an empty room. If the hotel is not willing to give us the room at the price we want we should not lie to them to get what we want. Neither should we take advantage of their failure to ask us for the appropriate ID. Our taking a hotel towel which no one asks for at check out is still stealing.