When to say when

While I always try my best to take care of everyone that comes through my door, there are often people who just make you cringe every time they pull up. Sometimes its the way they smell, sometimes they are just mean people, and sometimes they just plain suck when it comes to knowing how to act in public. Usually it is a lack of upbringing from their parents, but sometimes it's a case of becoming so bitter with society they now figure everyone else must suffer as well. I have one customer who has unknowingly perfected the most irritating expression known to mankind. Every worker has hated him, and it's always for the same reason. He is just plain ignorant. While he is very inconsistant in his demeanor, you are always guaranteed to see that one expression at least one in five trips. Normally that would not be bad, but considering he comes in at least 3-4 times a day you will experience it pretty regularly.
Unfortunately he enjoys confrontation and actually thrives on it as well. By fighting back you are only incouraging him more. While I fought for a long time I finally figured out how to handle this pathetic individual. Somehow I myself mastered a look so sad it instantly breaks down his front and causes him to actually be a normal human being during the rest of my transaction. I, myself now only see this expression maybe once a month. Unfortunately he now saves it for the other workers. I have learned to appreciate him as he forces me to delve deep into my head to stay one step ahead, and not let him get to me. For this I am actually thankful, however teaching a clerk to handle the situation in the same manner instead of the normal "fuck off and die response" is actually an even greater challenge.