I kept over compensating with left rudder and spinning it the other way. Consequently the US instructor would not check me out,
A lot of the exercises that crop up during checkouts are intended to allow you to demonstrate to the Instructor your ability to control the aircraft. Whether the exercise is steep turns, slow flight, power-on stalls or even PFLs.
If you mishandle the aircraft whilst demonstrating any one of these manoeuvres then you should congratulate yourself on having identified a weakness in your flying that you were evidently unaware of. Attempting to question the applicability of the exercise is not the right response.
In passing, it is interesting to note how many JAA PPLs struggle with the ground reference manoeuvres required as part of the FAA PPL syllabus. They are not in themselves difficult, but they often reveal flaws in pilot technique that are not demonstrated by going through the standard Uk/JAR instructing menu.
It sounds as though you have a thoroughly useful checkout!
2D