I don't think animals should have to tolerant having a stranger in their face or touching their face. I know that if a stranger or someone I didn't know very well tried to touch my face or other regions on my body I wouldn't respond very nicely. Step back unless I can't move back, tell them to stop and if they didn't I could very well do nothing less than knock the hand away etc.
I don't allow strangers to touch my animals especially their faces or get in their face unless the dog is telling us that is what they want. I also don't allow it with people that my dogs know just a little bit, until I see those signs.
This is also the explaination I give to all my students and to anyone else that will listen lol.
Where my animals are concerned I DON'T make requests of people, its my way or the highway.
What has amazed me for years is the fact that most people (adults) would never even consider approaching a stranger or someone they know a bit and touching that persons face, but they will do it with animals and then be surprised at the response.............go figure.