Been smoked in. Get an air freshener.
if it has air-con it might need a cleaner through it,its like a smoke bomb you let off in car whilst air -con is running.
Ah if it went and came back then it probs wont be smoke related.
Aircon need cleaning etc. Out of my depth now.
Have a swatch in the passenger footwell, see if it's damp.
Probly sex juices