Believe it or not, out of the 16 years I had her, my oldest dog only bit me once. She would sometimes bite other people, but for the longest time that was one thing she would never do to me. I was the only person who could pick her up or give her a bath, for example.
The only time she did bite me, she was really old by this time and was laying on my parents bed. I was trying to get her off because they wanted to go to bed, and she made it clear she wasn't going anywhere. She was really old at that point, and it was probably pretty painful to get picked up - so I could see why she snapped at me.