th,
I've never been attacked by a dog and I don't think I know anyone who has been. I have owned, bred, and raised large dogs, mostly german shepherds, without a serious incident. I'm around dogs frequently. I just petted one 10 minutes ago and I spent yesterday evening with 2 dobermans. I don't think my opinion is based on inexperience.
Attacking humans is unexpected behavior for domesticated animals in general and when it happens in the case of dogs it is also unexpected and usually is limited to dogs who have been trained to attack, which I think makes it an unnatural behavior. The vast majority of dogs aren't trained as attack dogs, although we rely heavily on their territorial instincts to create a lot of noise. So, actually being attacked by one seems like betrayal to me. In this country it is deemed unacceptable behavior and dogs that attack humans are frequently destroyed on the basis that they can't be trusted, which ties back to the idea of betrayal.