I worked in a factory which made these obscure little metal shafts and screw type thingies. The shafts eventualy would wind up in the little motor that runs the power windows in your car, or that makes your windshield wipers go. Anyways, my job was to 'sort' these parts. So if a customer complained they found some rust on the shafts in their shipment from us, they'd send the entire shipment back. I would then have to inspect each and every shaft, and take out all the rusty ones. Just one day of sorting thousands of shafts was enough to drive you insane. It was so tedious.