Take your time with these, but since maybe nobody else has asked I will do it!
ZANIE! The darling. I bet you can't get machine oil off from her. Do you think she tries with something else, though?
Bonus: If it hadn't been answered before: Hugin. :D
I told you I wouldn't abandon these fully!
For Zanie, I totally agree she's got that machine oil permanently ingrained. Combine that with a bit of a musty smell from being underground so long. But, now that she's a representative of the village and living above ground, I think she has a bit of fresh grass mixed in with the smell of oil, plus maybe a smokey scent from working the forge.
Hugin is unique considering he is in 3 separate locations thus far!
When we first meet him, he falls into the category of the rest of the Rustport cast. I know we love these characters, but according to canon, everyone in Rustport stinks of fish prior to the sewer side quest. So when we meet him, he smells like fish and machine oil. Once that gets fixed though, I think it's just machine oil and metal, with a bit of that smokey forge scent!
In Whiteridge, that sticks with him, but it's possible that scent is less pungent simply because of the cold, dry atmosphere not carrying it as much. He would be around the fire more with the weather, so maybe the smoke scent would be heavier.
In Brimstone Village, the machiney-smokey scent is more aromatic again, but mixed with fresh air and also some of the fresh meat and beer that is their specialty!
Bonus: Hugin definitely has a different scent he's assigned to each of his tools as their favorite, too.