The purpose of a job description is to attract employees who are willing to perform the specified tasks.
Job descriptions aren't supposed to be a vague guidelines to force employees to be wage slaves. If you want someone to do something: dangerous, disgusting, terrifying, or anything else unappealing, pay them more money.
You want me to show up? Pay me a basic amount of money.
You want me to do what you tell me to do? Pay me enough to cover the gas, the food I had to eat, the clothes I have to wear, the money it took to make those clothes presentable, and enough money to cover basic living without amenities.
You want me to do what I am not willing to do? Pay me enough money to put a smile on my face every once and a while.
Finally, you want me to smile for people who are blatantly rude to me, not cuss them out, and take your orders without comments or objection? Negotiate a contract with me that allows me to offset the negative emotions I have to face while dealing with the mess you want me to deal with.
Don't write a job description literally can be construed as wage slavery. If I can't afford to lose a job, then its not a job its a slave trap.