Back when My dad helped me build my 1st motor, he made me wash the whole socket set untill they were spotless. you only have to look at the crap a well used socket can leave on a nut/bolt to see the logic behind it. (As mentioned previously) Also the bit about having a well lit work area is a great point too. I just took to the fluro tubes in my workshop with a rag and a can of brakeclean. It's amazing how much more light they throw off when they are clean.