If the author had been blown into the face with stinking breath, it is doubtful that he would have liked this procedure. And animals are much more sensitive than us. What seems to us to be a light slap or whiff is equal to a boxing punch or a hurricane for them. In addition, most animals do not like close contact with someone's face due to the fact that their muzzle is the most vulnerable place in case of danger.
Let's start with the bad ones - it can snag or show aggression in any other way. I cannot single out any negative consequences for the pet's health.
The reason is that dogs have a very sensitive nose: it is not for nothing that they say that when attacking, you have to hit the dog in the nose, for them it is extremely painful. Also at the mouth are vibrissae (if simpler, the mustache), which are also sensitive to any influences.
Perhaps you might have noticed that if you blow on the dog's face, then it begins to cover it with its paws, roll or behave in some strange way. Do not confuse this with playfulness, the animal is trying to show in this way that it is unpleasant.
Therefore, I strongly advise against doing so.