How on Oerth do the Grimlocks in Three Faces of Evil target light sources? They can't see them. They don't even know what light is.
I guess torches crackle. Lanterns can hiss and sputter. Bot give off heat. I guess a sunrod could make some kind of noise. But wouldn't those require some kinda role to target AFTER some kind of training (Those sticks in their hands that make noise and give off heat, hit THEM).
But what about spells, etc.?
I can see creatures with Darkvision targetting those not so blessed, but creatures who have no idea what light is?