I've had a fire eater, Hudson. But sometime it's the operator. I used to train with Terry Christopher and Dan Keilty. Hudson would not creep on them at all but with me it was game on. He would growl at Terry. He could hear Dan's voice from 50 yards away and he would start growling.
After this experience I started evaluating to ability to be trained to be steady with both the sire and dam before I bought a puppy.