I live in South Florida. My home is a one level, 2400-sq ft, u-shaped with bedrooms on one side and kitchen/laundry on the other side. I have a consistent odor but it's not constant. It comes and goes and is isolated to the kitchen area. My laundry room is adjacent to the kitchen, so my wife seems to think that the odor is more prevalent when she does laundry. I haven't made that connection. I have called in several plumbers for their thoughts and nothing was resolved. One plumber found a small leaky pipe under the sink and repaired it, but that was not the solution. Is there a specialist in "odor detection" who could diagnose the problem?
Don't underestimate the detection abilities of your nose! Get on your hands and knees, and stick your nose right into every nook and cranny. Closing your eyes will help make your nose seem more sensitive. Smell along edges, cracks, baseboards, pipe cutouts, switch plates, jambs, sills, light fixtures, drains, and anywhere there's a gap or mating of any kind. Pull out the frig, dishwasher, washing machine, dryer, or remove their base plates and check underneath with a flashlight. Check the washer drain hose and drain pipe. Pull out all drawers in case something fell inside the cabinets. Don't forget outside walls too. Check any attic or basement or crawlspace. Cover every inch, and sooner or later you'll zero in on where the smell is definitely strongest. The source can't be far away.