The Modern Manners Guy technique for returning food without shaming the waitstaff (or getting a dollop of the "chef's special sauce" in your soup).
Q: I’ve suffered through too salty soups and room-temperature hamburgers because I’m worried the waiter will take offense and spit in my food. Is there a polite way to return food at a restaurant?
A: First of all, don’t be afraid to be honest. If the food isn't up to your expectations, tell your waiter – after all you're expected to pay for it. The server will not take umbrage with your complaint as long as you remain polite. Don't be wishy-washy and expect your server to offer his or her own idea of what might make the situation livable. That is confusing to the server and the options will probably not appease you anyway. He or she will wonder for the remainder of service whether you are happy or not, which is stressful.
Tell your waiter exactly what is wrong with the food: it's overcooked, it's too salty, it's cold, or maybe it’s even the wrong dish.Try something to the tune of: “Excuse me. I ordered my turkey sandwich with mustard instead of mayo. Would you please ask the cook for a sandwich with mustard? Thank you.”
Waitstaff generally enjoy customers who are easygoing even if they do require a little more work. Only if you adopt a sour attitude and bark at the waiter will you get on their bad side. Being rude, demanding, and hard to please are easy ways to get lousy service–and to be clear–you'd deserve it.