I went in to pick up an online order I had placed days before and the man that was working the front desk was rude. When he asked for my last name I spelled it out for him because the majority of the time people mispronounce or misspell it. He typed it into the computer and couldn't find it so I then proceeded by saying my last name and he found my order but told me I should have just said my name instead of spelling it. I was being nice and trying to be helpful so why be a jerk?
I also have a job where I deal with customers that can be difficult but I don't let it affect how I treat the rest of my clients.