You're expected to greet people politely.
Paul is a cashier at a liquor store, and a customer walked up to him .
Paul wants to greet the customer.
"Paul smiles at the customer and asks them, ""What would you like?""."
"Paul looks at the customer and asks them, ""What the heck do you want?""."
The customer thinks Paul is polite and is more willing to ask them for help.
The customer thinks that Paul is rude and is put in a bad mood.