Really? You're not just being facetious?
I NEVER send food back if I just don't like it. If it's under-seasoned or not up to my standards, no big deal. I'll go elsewhere next time.
But if it's a food safety issue, or if I order something pricey and it's missing a key ingredient (they don't have to take it back in that case, just bring that ingredient to the table and we're good). I mean, if you paid for it and you can't eat it because it's unsafe or you didn't get what you paid for ... that should be totally understandable and expected that it gets sent back. I've worked in food service and while I would never spit on anyone's food no matter how much of a dick they are, I wouldn't even feel the temptation if it was a legit kitchen screw-up.