What they smell isn't the emotion of fear. What dogs can smell is the changes in a person's skin that suggest fear to the dog anxiety the way your skin sweats the amount of uric acid that suddenly pours out of your pores.
We have enslaved the rest of the animal creation and have treated our distant cousins in fur and feathers so badly that beyond doubt if they were able to formulate a religion they would depict the Devil in human form.
