"Dust is a Must!" That's a common phrase used by cornhole players when discussing the dust that comes off of a cornhole bag after repeated use.
As the feed corn inside the bag breaks down, a fine dust is produced. Many people feel that this dust makes the boards smoother, and creates the best game play. Many people also enjoy watching the plume of dust that will rise off a big toss.
Some people do not enjoy the corn dust, and will use alternate bag fillings.