I only take it back if it's not what I ordered. It doesn't happen often because most people who make a living taking orders know how to take an order. I can't remember the last time this happened to me, actually.

EDIT: Oh, it happens on rare occasions with takeaway places, now that I think about it. Normally it's a case of forgetting something rather than getting it wrong and they just come back with whatever was missing. I remember Danielle once got onion on her pizza which she didn't ask for and we got a voucher (and the right pizza) along with the right pizza, which was neat. It pays to complain if people get things wrong.