Being extremely concerned about appearing rich but having absolutely no idea how to do it is basically the defining outwardly-visible characteristic of the midd

Being extremely concerned about appearing rich but having absolutely no idea how to do it is basically the defining outwardly-visible characteristic of the middle class (in a Fussellian sense of "middle class"). McMansions are a perfect expression of this: trying to look bigger and fancier than they are while being extremely cheap in every way that matters, and getting every "fanciness" signal all wrong. They're a common target because plainly-inept pretentiousness is very funny—it's a staple trope in comedy for a reason. It's not the size of the house per se that draws comment on McMansions. It's the intense and desperate but hopelessly misguided social signaling in their styling.