That cashier probably didn't think her language was offensive. Unfortunately, these days, many people think the f-word is acceptable in general conversation.
Safeway pharmacies have a sign beside the counter: "Please end your cell phone conversation before speaking to the pharmacist." Do people really need to be told that? I guess so.
I've pretty much given up on expecting good customer service. I no longer shop at the Body Shop because of the rudeness of one of their managers.