Skittles, sorted by hand? Absolutely unacceptable. The year is 2015 and if someone wants to sort Skittles (or M&Ms) it has to be done with a 3D printed machine, like the one Nathan Peterson built.
Everything is 3D printed except for the electronics. It uses a TCS3200 for colour sensing. It is powered by 3 DC motors, and has some additional sensors to detect the positions of the discs and to tell when a skittle has been dropped.
Questions such as why would someone sort Skittles by colour are better left unanswered. It's an impressive funny little gadget that works well.