During my IR phase I flew with a guy who would tell you to pitch down (I was a bit high during a practice ILS), and seconds later he would shove his yoke forward when he felt that my response didtn't come quickly enough. It always managed to destabilise my approach, and I felt I never got the opportunity to learn. If my responses were too slow (they may well have been), it would have been better to let me figure that out for myself. I later managed to ditch this instructor, but not before he put a real dent in my self confidence. After the switch to a different instructor, I was back on track after two flights fortunately.
There is a big difference between assisting a student, for example by adjusting the pitch attitude gently while clearly taking over control and explaining what you're doing and why, and bashing your hand against the center of the yoke while yelling in the student's ear.