I remember reading a short story by Stephen King called the “ 10 O’clock people “ The premise was that all smoking had been banned indoors so that any remaining smokers had to smoke outdoors. At 10 0’clock the remaing smokers would go outside for a smoke. There were nefarious aliens who had invaded the world. They were able to shroud there appearance to look like humans however smokers were able to see through it and see the aliens true appearance. I will leave it at that in case anyone wants to read the story.
Why would smokers see them?