Engineers and scientists can look like scruff bags because they don't have to try and flog stuff to people. They don't need to do the slick, clean shaven thing.
Edited by Kieran XJR on Friday 12th September 10:28
They know something we don't about excess facial hair? Alternatively it's where they store bits of food for when they are too caught up in atoms to get away for lunch.
Is it because all scientists drive Volvos and you aren't allowed to buy a Volvo without having a beard in the same way you aren't allowed to buy a Hyundai without showing a pension book?