It’s going to come down to the individual small molecules that give the cologne it’s aroma. I suspect most of them have some sort of metabolism pathway, either by our own bodies or by the flora that inhabit it.
Someone mentioned capsaicin. That’s mostly metabolized. But we can experience breakthrough if consumed in excess.
Myself, my shit simply does not stink.
My father used to tell me there was a problem back in his GI days with guys in some of the barracks getting their aftershave stolen out of their lockers by alcoholic soldiers. The aftershave contained alcohol. I suppose cologne does too?
Seems like a good place to ask, do fart pills (to make your farts smell like flowers or chocolate) actually work?
I think it’s common to use isopropyl alcohol as the diluent. It’s not as bad for you as, say, polonium, but less than an ounce is enough to start making you sick.