About a year ago I put a plastic office floor protector in front of my desk to help the chair move over the carpet. Several months later the plastic began to crack so I pulled it up. Immediately I began smelling mildew or musty smell. Upon checking around the carpet I discovered that the smell was only under where the plastic mat sat.
My house is on a concrete slab foundation. I discovered recently that the concrete sweats badly where ever the floor was sealed with tile or in one case a room where I put down a floating wood floor with the vapor barrier. Under the barrier water pooled so bad that it collected near the outside wall and was drawn up into the floor. I have checked and found no leaks in the house. In fact, the tile I layed in the foyer began to curl up and water would squirt up through the joints in the tile whenever you walked on it. The concrete was so wet that I just pulled up the tile with no trouble. I checked all around the area where the tile was and the concrete was totally dry. This convinced me that the concrete sweats very bad whenever it is covered and air cannot get to it. As a fix, I sealed the concrete and reinstalled a new tile floor. In the room with the wood floor, I sealed the concete, reinstalled the vapor barrier,and put down another wood floor. Since then, I have not had any problems with water. However, I still have the problem with the mildew smell in the carpet where the plastic mat sat. I have tried nearly everything from vinegar to professional strength odor remover to get rid of the smell to no success.
Any ideas short of replacing the carpet?