What is the right etiquette for refusing a room?

Possible reasons:
* Not as impressive as pictured (as hotels often show the best room in the category on their websites)
* Layout is unexpected
* View is inferior
* Noise issue
* Maintenance issue
* Low ceiling height
* Bathroom configuration unsuitable

I assume most hotels would be happy to show other options in the category booked or even grant a minor upgrade. However, assuming that the hotel is full booked or is unwilling to budge, or if one is not willing to pay for the differential to upgrade, does one have the option to leave if the room is booked but not prepaid?

At luxury hotels, the staff showing one to the room would often ask if one is happy with the room. What if one says no?

I don't intend to do this unless I feel the room is completely misadvertised, but wonder.