Help Me Understand

"People are people so why should it be, you and I should get along so awfully?"
People think I complain about my job. I don't. They complain I whine a lot. Wah. They say I should get out of retail. They say I hate my customers. I won't and I don't. It's like having favourite family members. You always smile at the reunions, shake hands and give hugs and kisses, but secretly you're whispering behind their backs about Aunt Flo and her surprise visits, the overprotective Uncle Owen, and Miss Havisham with her wedding issues.
Every day we walk in to work with a smile as bright as the sun. Every day, customers work to erode that. As dawn turns to the noonday sun, bright and high, then lowers in the Western sky, so too, our smiles set as a once hopeful day dies in a sky of clouded pitch. We are not the staff who entered our stores some 10-14 hours earlier. We are officially walking dead as we exit into the night.
How does this happen? The majority of our customers we love. Rather, we like them. Okay it's like a Bell Curve: 5% Love, 20% Like, 50% Accept, 20% Tolerate, 5% Loathe. Give or take on any given day. Who are the ones that ruin it?

"It's obvious you hate me though I've done nothing wrong. I've never even met you so what could I have done?"
Seriously. I'm new to this store. Already you're bitching and screaming at me as if I have personally ruined your life. Calmly and quietly take a step back, take a breath, then come back when you're ready to act like an adult and I will try to help you. If I understand the problem, I can explain it and attempt to fix it. Muttering under your breath that I'm trying to kill you, that you don't know why you come here, that there's a problem at every pharmacy you go to, that your doctor wrote it so you have to have it only indicate to me the problem is seriously YOU. If you do not attempt to understand the problem, if you do not listen to the explanation of the problem, if you are too stubborn to be wrong, we are going to remain at an impasse. Your blood pressure, along with mine, will only continue to rise. Therefore, in order to save us both a lot of health issues, I rescind your invitation to use my pharmacy. You have officially been uninvited. Like the life-sucking vampire you wish to be, you must leave now. It is the official rule of the undead. Please pack your knives and go.