Japanese Observation #4

A great many Japanese people over the age of about 40 suck their teeth after eating, particularly salary men, particularly on the train. This seems to be the sole preserve of the upper adults of society - I have yet to see any teens or twenty-somethings do this. Where such a thing to transpire in England, it would be seen as the height of bad manners, especially in public. However, were I to do something as innocuous as silently dab my nose with a handkerchief, I would be commiting a grave social faux pas, and the said salary men would blink daggers in my general direction. How strange!
This teeth sucking also seems to function as a defense mechanism, started perhaps when the sucker (as it were) feels uncomfortable in the presence of foreigners, much as someone else would start toying with their mobile phone or start whistling.