Symbolism, Imagery, Allegory
Dwight's "trunkful of paint in five-gallon cans" (11.37) gets applied to his house in truly ridiculous ways. He paints the ceiling, the walls, all of the furniture, and even the keys to the piano… "all except the black ones, of course." (11.47) The overkill is supposed to impress Jack's mom. But it's overkill nonetheless.
More importantly, it's supposed to cover up the horrible reality of Dwight's world with shiny bright happiness that no one can ever, ever, ever displace. Ever. Of course, it doesn't eliminate anything. It just covers up the rot for a while until it all comes crashing out in hideous ugly ways. Pretty good description for family life under Dwight, isn't it? It's also a good sign of how Dwight thinks he can hide all that…