Welcome to the Kingdom of Doodsdpogi

The wealthy had slate floors that would get slippery in the winter when wet, so they spread thresh (straw) on the floor to help keep their footing. As the winter wore on, they kept adding more thresh until when you opened the door it would all start slipping outside. A piece of wood was placed in the entranceway. Hence the saying, a "thresh hold."

The floor was dirt. Only the wealthy had something other than dirt. Hence, the saying, "dirt poor".