I recently witnessed a confrontation between disembarking pax and cabin crew whilst on the airbridge, over remarks made about the attire of one of the pax.
This was escalating until the Capt appeared out of the flight deck and as if by magic the mood changed.
I do think that the four bars command a sense of respect in most people and to be honest defused the situation in this case. (Someone ate humble pie)
I was taught that " Courtesy is an essential quality, and one that will smooth many a path" maybe this sort of attitude should be adopted by more people in order to avoid this sort of situation.