you wont actually SMELL the ammonia unless you have kidney problems or something.

What he's probably smelling is just a mixture of mucous, dirt and sweat.

The ammonia reference is a metabolic byproduct of metabolism. It comes from lactic acid. The ammonia is converted to urea by the kidneys and excreted as urine. If someone had enough ammonia in their system to actually SMELL it...they are probably already dead.