I recently found an interesting thought on this topic that emanates from the Divrei Chacham Tzvi. The polite way to suggest to someone that they are doing something wrong -- particularly if that person is a parent or one's rabbi, whom one should be at pains not to contradict -- is to ask them a question, posed in abstract terms, about the conduct one wishes to draw to their attention. This question would run along the lines of "can you please teach me the halachah (the Jewish legal position) regarding such-and-such?" Ideally, in giving the correct answer to this question, the "offender" would suddenly realize that the answer applied to him or her and would instantly refrain from whatever should not have been done.
"What has this to do with Pirkei Avot?", you may be wondering. The answer lies at Avot 4:1 in the maxim of Ben Zoma: "Who is wise? The person who learns from everyone". This is said here to apply to a person who has the capacity to "learn" from everyone by asking them for a ruling when he or she is actively involved in rebuking them.
This explanation is pretty certainly not what Ben Zoma had in mind. However, it has the highly positively effect of encouraging people to administer rebukes to anyone and everyone who may need them, irrespective of rank and status. It also emphasises the importance of putting people back on the right course in their religious commitments.
In terms of practical application, this explanation is bound to be narrow. While it applies where a person is making an error under Jewish law, it is not easy to see how it could be made to apply in situations where human behaviour involves choosing between a range of possible options.
