I can think of no way sewer odor would get past properly filled traps. Is it possible there is a leak in the drainline under the house? If there is a leak, gray water would pool and smell musty. That is not the same smell as sewer gas. I would not describe sewer gas as, "musty". I've experienced dry traps letting odor in, but the smell was gone almost immediately after charging the trap with water. Check the crawl space.