I'm with some of the others here: if they try to assign you a room with a connecting door, just refuse it. (If I walk into my assigned room and see "the door" I go back to the reception... immediately...)

I don't even see why hotels need those rooms?
I can guess the answer: families with children maybe? If that's the reason, they should assign them to those that need them, even when they are traveling alone. I have no need for connecting doors, never asked for them, and should not be bothered by them.