Reading about foreign material in oils reminds me of videos I’ve seen where the wood for distillation gets chopped up on the ground, and carvers smoking while carving, and carving dust on the floor, probably swept up to make oud. Their feet also used to hold the wood in place.
Even if you wash the wood shavings before distillation, I imagine all sorts of matter, critters, and cigarette butts get inadvertently included into the pot. Hence, Tobacco Note
Lastly, some Distillers filter the oil before decanting. Can you imagine what was left in the filter
But I’m not complaining. If you needed a sterile laboratory to distill oud, then the price of the oils would double or triple