Alain Corbin, in The Foul and The Fragrant (1986), writes of nineteenth century France:
"Oddly, medical discourse concerned itself little with the specific relation of smell to temperament, the color of hair, or complexion. The odor peculiar to irascible personalities and the smell of redheads were noted, but without emphasis, as if they were self evident."
He later adds, "redheads were always pungent, both putrid and fascinating, as if their cycle had broken down and put them in a continuous state of menstruation."
We also found this interesting tidbit on the Net:
There is a study done by a scientist which states that the color of a canine has a direct effect on the scenting ability. For instance, a white canine does not possess the same ability to scent as does a canine which is darker in color. That is one of the reasons you will never see a white canine in police service in foreign countries. The pigment of the canine's skin or hair has a direct effect on his ability to smell. (Bill Syrotuk)