If customers get upset with you for whatever reason I have found they are upset before they ever walk in the door. You are just convenient to take it out on. Certain customers look down on you because they are under the impression you are just the hired help and need to cater to their every whim.
Don't. It's not the job it's certain management people. The job is easy and mostly fun. Low pay.
Look somewhere else, pay sucks. All about bottom line, not workers.