Hello, Bernard,
I also discovered this: It is not that difficult to get rid of bad habits, if the good habit is indeed a good habit.
I agree with you in general, but there are a few bad habits that are incredibly hard to fix. One is "dragging the fingers" in scale work, where two or more keys are held down because they are not released properly. However, I find this is usually a problem for adults (or older teens who are physically nearly grown). I think I could come up with a few other bad habits that are very hard to change. The difficulty is related to how long the habit has been "practiced". In short, people get very good at doing what they practice hard at for a long time. So if what they are practicing is wrong, they become very "good" at doing it wrong.
I especially liked what you wrote here:
“I can’t do that”. The most frequently heard sentence in the whole student vocabulary. My answer: “Of course you cannot, you moron! That is why you are a student, and that is why you came to the course in the first place.[…"]
I say much the same way, explaining that I don't expect anyone to do anything until I've showed them how, and I also mention that it was the same for me, as a student.
In another thread you linked, you mentioned consistent fingering. My teaching also matches yours here, I think. My advice: "I would prefer that you follow the fingering I have given you. As you become more advanced, I will not only allow you to change the fingering I recommend, I will often encourage you to experiment. But you must stick to what you choose, because changing fingering later on can be incredibly difficult, and if you change fingering each time you play a piece, you will confuse your brain and it will not know what to do under pressure—even if the pressure is no more than showing off for your family or a friend.
Finally, I very much like this:
"Unless a student loves to bits the piece they are assigned they will not put any work into it."
I have only one thing I'd like to add to this. My students often enjoy playing things they believe they only like "a little bit" if they are able to learn them quickly and play them very well, because they impress themselves. For the same reason, students who insist on playing things that are too far above them may become so discouraged that they never want to play them again, even later. So if someone insists on playing piece he or she is not ready for, in my opinion, I will sometimes allow them to do so, but I will also say after a lesson or two, "Are you sure you wouldn't rather wait a bit until you are more advanced, because then this 'favorite piece' will no longer seem impossible to play."
What I was really looking for was experiences from other teachers faced specific problems they inherited from other teachers. By the way, if a student comes to me having been poorly taught, in my opinion, I NEVER say that. I simply say, "Well, I see that you have learned some things we can use, so I hope you won't mind as I suggest things we can add to what you have already learned to make things better."
Gaer