Can a male dog smell a female dog on another dog?

It depends. When a dog smells it is trying to gather information on where the other dog/person has been. I can tell you for a fact that when I come home from work (a veterinary clinic) my dogs won't leave me alone until I change. But still they can not decipher on what sex of animals you have been near unless say the female dog was in heat. If you happen to get some of that female's urine/ other bodily secretions then YES! a male dog will be able to tell you have been near a female, but if the female is spayed for instance, then all the male will be able to tell is that it is another dog, not necessarily if it's a female or male.