I had a bull terrier living around the corner when I was growing up. She was the friendliest dog you could ever wish for... she recognised me and always wagged her tail furiously (that's in a good way
) when she saw me.
The only time she ever hurt me was when she got a bit excited and "bopped" my nose with hers... but that was pure excitement, nothing aggressive... I was just a small kid so it hurt a bit more. I still have some photos of her in my old albums.