An air conditioner should not smell like smoke when turned on (or when turned off). I would have to suspect that the electrical insulation is burning.
Animals that breath air would not . . . if they tried, they would drown. Animals like fish would smell sulphur in water.
there is a leak in the compressor...
if u would have noticed the onion smell comes only when you cut onions .
There are a number of reasons why air coming up from air vents would smell like dead fish. The air ducts may need cleaning. The air coil may need replacing. It could even be an electrical problem with the unit.
Presence of sulphur.
It sounds like there is a leak inthe evaporator section of your air conditioner. If this continues, the air conditioner will no longer cool and you may have to replace several components of the system. The smell is that of atomized esther oil.
Compressed air used for SCUBA should smell like regular air. There may be a slight rubber smell from the regulator. When in doubt, it is safer to get your tank refilled than to dive on contaminated air.
Some people like the rain because of the cold wet drops running down your neck, and the smell of the wet grass filling the air.
Cats spraying your car with urine.
you would smell very dirty air that would mostly give you the plaque
it smells like a fresh grapes