Nothing in this Part shall apply to:
(1) What is commonly known as a rubber boot or shoe, or to the use of a rubber heel on a boot or shoe; or
(2) The use of steel, wood or other substance as an inside filler in the shank of a boot or shoe; or
(3) The use of cork or cement between the soles of a boot or shoe; or
(4) A retail dealer who unknowingly sells shoes which although properly stamped are in violation of this Part.