Homely as a mud wall

The meaning seems obvious, but has anyone ever heard "she's as homely as a mud wall" and what in the world is a mud wall? Thanks. Jonathan

A wall made of mud, presumably. Mud huts is the basic local building material in huge areas of Asia, Africa and the Americas; quite large and sophisticated houses can be made of mud. This must be a purely Leftpondian saying, as in Britain "homely" isn't used to mean "ugly".

I've heard -- in West Virginia -- ugly as a mud fence.