Years ago, I was the director of operations at a flight school in Miami. Lotsa students from the Arab countries and Africa. Until they got “The Talk”, they often stunk so bad that you could barely stand being in the same room with them (not to mention a Cessna 152 on a hot day).
The commonly would wear a shirt for a week at a time. Same grease spot, day after day. (Don’t know about everything else.)
Imagine the germs on every pencil and paper, desk, plane instruments, restroom, door handle, etc. Ugh.