Apparently grad students have depressing homes

From The Man Who Gets The Science Right On 'The Big Bang Theory':

[David Saltzberg] got involved with The Big Bang Theory in 2007, when the show was little more than a theoretical construct. The set designers asked him to show them some real graduate students' apartments, so they could see how young scientists really live.

"And they did a nice, faithful re-creation of their apartments," he said, adding that after CBS tested the show, the sets were scrapped, because, Saltzberg thinks, the sets were too depressing.

Probably tangential, but it never quite makes sense to me why people (probably occasionally including myself) are so particular about cleanliness when visitors stop by.