I had an experience with a chap who was going to instruct at our club. So i sat with him for some local familiarization, he nearly stalled in at 6 feet above the runway until i woke up grabbed hold of the controls and recovered the situation. He admitted he froze on the controls. He later became a Captain with a well known small airline.
Another chap who stuffed an aircraft into a hillside in imc, wanted to get airborne after his long recovery from hospital.
We entered imc whilst flying and he was quite happy to descend over high terrain whilst still imc!
Both of the above where UK trained instructors.
No matter where they have been trained there will always be some pilots who who are crap.