I can understand any bite if it is unintentional (dog is in pain, given a fright, or missed the chew toy). Rex being a CD can get mouthy, though it doesn't hurt or penetrate any skin. One time Molly out of the blue was hyped up by Rex, jumped on the couch and bit the side of my arse! and then looked at me with her big cheesy grin - dunno what to make of that cause it was kinda intentional, but not really? Any other dog we've had in our family i have never been bit.
I think if you were ever savaged by your own dog that would say a lot about what sort of dog owner you are! Even dogs that are being treated badly and are abused usually still have great loyalties with their so called 'owner' who's dealing the abuse.