Well, good point. But its best if you can be relatively confident that even if someone runs up and pounds your dog on the head, they still won't bite. We don't all have that luxury, but there are definately some dogs who would just wag their tails and some that would take your arm off.
That said, I don't think we have many unprovoked biters on Chaz. Biters in the situation above probably. Dogs that would bite if actually threatened, certainly. Which ones . . . I'm not sure. I'm not even totally sure what Sarama would do. I'm fairly sure with an overfriendly stranger she'd retreat and not bite unless pursued . . . unless perhaps they actually startled her by coming out of no where. If actually attacked . . . by a human, not sure . .. by another dog, I'm pretty confident she'd fight back. If I was threatened . . . well, she had certainly done things to make me think she'd protect me from another animal, and the one time she thought we had an intruder in the house she sounded very fierce . .. but woudl she bite? I don't know.
She's also only 10 months old . . . so who knows what she may be like a four? Bomb-proof I would hope, but willing to protect me, or herself, from an authentic threat . . . or at least look and sound like she would!