They've always frowned on it. We had a regular procedure called "heads down!" in which all children or occasionally just three of us would duck down so as not to be visible in the car from the window of the motel office. When my brothers and I travel together now we still do it (mostly) as a joke.

Having stayed in a motel a lot over the last month, I'm pretty confident most parents could get 4-5 kids into most hotel rooms without management being the wiser.