We have the strangest odor in our TT...it smells like an ash tray! (That's my best description.) We bought our TT in March, obviously used from CampingWorld and we were able to go into it and look ...
If it came up all of the sudden it could be a drip/leak causing mold, or overflowing water from the refrigerator drain line or evem condensation leaking onto carpets from "sweating windows".