Will you let your dog/a dog to lick your face?

Everyone who own a dog/dogs will know that their dogs love to lick their owner’s/someone’s face as their sign of affection. But if your dog/someone’s dog(could be a stranger) suddenly wants to lick your face(included your eyes,lip,nose,etc) will you honestly allow them to do that?,if yes,will you let your face unwashed for long time?,will you judge them by looks,size,owner,or else?,any regret/concern if they lick your face by accident?,and what do you think about their saliva?.