Hiya Matt
I know that smell. (sounds like a bad Jr high school game...)
Every so often, Shorty gets a dragony smell.
Not enough to bother us, but it does have a distinctive aroma when you notice it.
But it never sticks around very long either.
I do not notice the outdoor dragons having this smell, but both are in high-ceilinged, well-ventilated (leaky) spaces.
Also, both are first-gen designs; perhaps this is unique to the Shorty design?
An oddball idea might be to place a tin of baking soda through the cleanout door and see if that helps.