Allowing dogs to lick a person in the face

Question
Dogs licking a person in the face and primarily on the lips.

My children see no problem at all with allowing our family dog to lick them in the face and will not stop our dog from doing that. My argument to that is that you shouldn't even let a human lick you in the face much less a dog. Thier argument and my question is, isn't it a urban rumor that a dogs mouth is cleaner than a humans? I can not see how this could be possible as dogs will eat some pretty nasty things as cat poop seems to be a delicacy to them among other nasty things. And then they ge straight from eating things like that or licking their own private areas to licking my kids in the face. I've never heard of any tranmittable disease from a dog to a human but I would think things like diarrhea could be caused from allowing a dog to do this.
Please let me know if my concerns are correct in allowing a dog to freely lick them in the face. Also to solve whether it is a urban rumor or not please let me know if a dogs mouth is in fact cleaner than a humans.
Thank you for your time to review and answer my question.
Brian

Answer
Hi Brian,

I have to confess I grew up being licked to death by my dog, and my children have too. We seem no worse for wear. As far as a dog's mouth being cleaner, naw, I don't think that's so. I am not a vet, however. I do think we just get different diseases, for the most part, we we don't catch colds from dogs. I do caution you to make sure your dog is parasite-free, as humans CAN get those from dogs. As I write, I have a big black nose trying to get into my face!Wash up before you eat! And enjoy the absolutely unconditional love of your dog.