4. He's mastered the art of organization.
Cleanliness is next to godliness, right? Well, for Sheldon, not only is cleaning a lifestyle, it's an ideology. The man believes that everything has its place, and he expects his friends to respect his scrupulous scrubbing methods.
The good news is, if you don't have the time (or desire) to clean, Sheldon's happy to sneak into your apartment in the middle of the night and organize for you!