Gnomes are only rarely involved with missing laundry socks.
One way is when they hide in a laundry basket and get transferred to the washer. Those "stubborn stains that don't come out" are actually gnome smudges. The gnome must wait to the brief moment when the water is draining (but before the spin cycle!) to lift the lid and escape.
The other way is when pursued by a housedog and they throw a distraction sock in one direction while fleeing in the other.