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 ...
When I think of a ash tray smell I think of a burnt smell. Have you been running the furnace recently? If so it may be burning off dust. Have you looked under the burners on the stove to see if something fell under there? If so not only will it smell but, it will get heated up each time you use the stove and make more smell.