
One of the trainers, I have spoken to about Scarlet, has suggested the following:
When someone comes, tell them to initially ignore the dog. Then shake that persons hand, and talk to the person. With your dog beside you, hand the "person" a treat, and follow the persons hand down with yours, so both hands (yours and the other persons) are offering a treat. The dog will do one of two things:
either take the treat (because there is a familiar scent coming with the treat, a treat, and this new scent)
or
Bite your hand before it bites the other person (hopefully). its a bit of protection for the other person. Also, you can better control the dog, with your hand down their as well.
HTH