Smells! I've had smells so distinct that I have asked others

Smells so distinct that I have ask others "is the smell of propane" bothering you?
Several times riding in a diesel Pickup asked the owner if there was an exhaust leak? another time in a deasel PU ask the driver if they smelled diesel exhaust?
Other smells; automobile exhaust; cigerette smoke & a specific pipe smoker smell.