Sheldon and Leonard may have social challenges, but the same side of the brain that makes them science geniuses must also make them neat freaks because there's no other explanation for how their apartment stays so tidy.
In the show, the boys and their geeky friends are constantly fixated on physics, science fiction, "Star Trek," comic books – and of course, neighbor Penny. Yet you never see them discussing whose turn it is to do the dishes, clean the refrigerator or empty wastebaskets. A parade of friends and family members can visit, hang out, or even stay for a bit but the house never looks the worse for wear. Maybe the guys have invented an unseen robot that does the chores.
While Sheldon and Leonard probably wouldn't have pyramids of beer cans, smelly gym shorts or footballs in the den, but dirty laundry, unmade beds and cans of Chef Boyardee should abound. Physics may provide answers to many of life's questions, but it won't explain the mystery of the pristine bachelor apartment.