Shoshin... heart of the beginner or mind of the beginner it is the foundation. Unfortunately everyone wants to be Sensei and there is always a "right way" to do things. Last time I checked however, the job of helping a student to a more efficient technical expression was the job of the designated instructor. If help is requested when that person is not aware... it should be honored and humbly offered. But, the instructor should be aware. If it is not requested (by someone doing something "incorrectly"), and they are only putting their own progress in jeopardy, it should not be "offered" unless you are the designated instructor. If they are putting someone in jeopardy... then it should be offered respectfully, immediately and then brought to the instructors attention. The confrontational language is never appropriate, but rude is as rude gets. Ignoring that stuff is far more effective. Too bad this crap is even an issue where a common goal is involved.