Dogs love to eat all manner of nasty stuff that they dig up or find lying around including their own and other dog's poops. They also have the propensity(and the physical ability) to lick their own butts and privates.
I don't see where a breath spray would have anything more than a cosmetic effect. So...no...I don't use a breath spray for my dogs.
If they lick my hands or face...and they do... I wash up.