Growing up we had one room that was off limits most of the time, though my mother wasn't nearly as bad as some of you were describing. We could use that room to practice piano/oboe/cello (depending on the kid in question), and that was the room that Christmas and Easter were always set up in, but for day to day use, it was off limits.
My mom also did the plastic thing, but at least she had a very good reason. For a number of years my grandmother (father's mother) lived with us and she had a "dribbling" problem and refused to admit it. Everything she sat on wound up smelling like pee, so my mother basically shrink wrapped every piece of furniture in the house. When Grandma passed away, mom uncovered everything.