If you design remodeling jobs it can be useful to have special walls for remodeling. In addition to my normal new design walls I also have sets for existing and demo walls. They have their own colors and fill textures to distinguish them apart. This makes it easy to see what is existing, what will be removed, and what is to be built.
This is also useful for SoftList users. Formulas can ignore the Existing walls and calculate a demo cost for the walls to be removed.