Has she ever gone after anyone? Professional thieves know that the vast majority of dogs are all bark and no bite, especially when their humans are not home. People are shocked to see their "guard" dogs get all submissive around a confident stranger in their territory. Treats make it even easier.
Oh nope. Even if she knows them, if I'm not around....it's not a good scene. And treats will do you no good, she will either go complete basket case (wuss mode engage, and yes submission peeing has been known to happen) and if she doesn't know you....you are not crossing the threshold.