your example is completely flawed. It assumes that the object of annoyance is obvious and in your example you tell them it was the foot. Sometimes its so subconscious people don't even pick up on what they say badly. Sure enough the person may not need a lecture but a quick comment on why what they said was bad I think is right.
To use the dancing example. Say the dancer has always been told to step back and causes harm unintentionally. Just saying sorry and moving on and continuating to step back is allowing the problem to continue and that person will teach those dance steps to others. However once you get hurt, just saying its the left foot to the side and not back is polite, informative and good for everyone who risk's their heels being stood on. Its still 'education' because you are telling something they don't know but its hardly a history on the genesis of the tango.
There are no hard and fast rules its just civility and common sense.