R.L. said:

"one of the other things I learned is the ability to smell cyanide is a genetic thing, not everyone can smell it..."

Some things you don't want to smell. I've been told that phosgene smells like rotten fish. I've also been told that if you can actually smell phosgene then you're dead (you've inhaled a lethal dose). I've also read that VX nerve gas has a pleasant fruity smell. How do people know this? They used to keep a hydrogen fluoride laser in the building where I work. About once a month, one of the toxic gas sensors would go off by accident and there would be the pell-mell race for the doors. We all cheered when they got rid of that damned laser.

Gary