I have a double sink- only one side smells constantly of mold/mildew. I have done everything (including take apart pipes and clean them which there was a tiny bit of black sludge). The smell constantly returns. The side that stinks is the side without the garbage disposal. When the garbage disposal is turned on I can smell it more. This is new plumbing. Before I call plumber wondering if this set up is ok? From my internet browsing most pics have the wall drain pipe on the side without the disposal. Ours is the opposite. Any knowledge /advice is much appreciated!!!