Sticking your hand out is not the ideal method to meet a new dog.
This is just another of the amusing facts about dogs that aren't quite accurate. You undoubtedly grew up believing that the old adage "reach out your hand to an unknown dog and let it smell you" was gospel. And it can work, but you must be careful how you go about it. Simply thrusting your hand in front of an unfamiliar dog's face might frighten or alienate her. Instead of presuming she wants to and waving your hand under her nose, you're better off letting the dog approach you first and then giving your hand for the dog to smell. And, if you must approach the dog, approach it from the side rather than straight on.