The lunar astronauts universally described the smell of moon dust as similar to spent gunpowder.
The exhaust gases from the LM's descent propulsion system (which combusts Aerozine-50 with N2O4) didn't instantly vanish from the landing site; it's estimated that the mass of the moon's atmosphere was briefly doubled by LM exhaust during each landing. (The RCS thrusters on the LM use the same propellant combination.) In addition, the remaining contents of the descent stage oxidizer tanks were vented shortly after landing (102:47 in this transcript).
Moon dust doesn't have a lot of nitrogen in it. Hydrazines, N2O4, and nitrocellulose/nitroglycerin gunpowders all do.
N2O4 has "a sharp, unpleasant chemical odor"; it vaporizes rapidly to NO2 which has "a characteristic sharp, biting odor". Combined with moisture in the astronauts' lungs and nasal passages, it could convert to nitric acid, with an "acrid, suffocating odor".
Is it possible the Apollo astronauts were smelling traces of their LM rocket exhaust, or the vented oxidizer? Call it the "who smelt it, dealt it" hypothesis.