Dogs have always made me weak willed and lilly livered. I just can't ever be harsh with them. Just too endearing.
I have been a dogsitter for about 17 years, and the only time I ever smacked a dog
was when I thought he was about to attack another. (It turned out they were just playing,
but the display of teeth scared me at that time.) Dogs are wonderful.
I had a dream last night where I tried to play with a couple of rottweilers, but they got scared when I play-growled at them, panicked and started fighting with each other.
My cocker spaniel has a bad habit of growling and snapping at other dogs, and she's been attacked twice because of it; once by a labrador and once by a pair of Staffordshire terriers (both times while my mum was walking her; it hasn't happened while I've been walking her). She doesn't try to hurt other dogs; she just tries to intimidate them and assert territorial dominance, or scare them off if they're making her nervous (which happens when large dogs keep coming too close to her).
She also sometimes growls and snaps at strangers who try to pet her; she's very friendly towards people she's familiar with, but she doesn't want to have anything to do with strangers.