It drives me nuts when people waste food for stupid reasons. If you're not hungry and you don't like leftovers, that's fine. If you don't like it, okay. But some people I just want to take their plate and dump it over their stupid heads.
A perfect example is a gentleman who came in a couple of weeks ago with his wife. They seemed perfectly pleasant, if ancient. I was pouring drinks when someone took their food out, and was about to carry said drinks out when the host radioed the manager saying that my old guy was throwing a fit and I'd better get out there.
"Does this look plate look grungy to you?" he asked me, his eyes bulging out.
I leaned over to inspect it, immediately worried. I didn't see anything, except ... "Oh, looks there was just a splash of sauce there."
"Well, I'd hate to think you'd serve food this way!" At this point his eyes looked like they were going to pop out from between his livid red lids. I was sort of surprised and blinked at him. "Look at this! There's no reason there should be any sauce! Not unless the poured it from up here!" He held his hand as high in the air as he could.
"I can get you a new one," I said, still failing to see what the problem was. Anybody with a brain could see a sauce-slathered noodle had slid along the edge of the plate, and that it was the same fucking sauce that had splashed on the edge of the plate.
"I'm not eating this, this plate is dirty." He was nearly yelling now. I kept offering to get a new one, and he kept bitching--and stabbing at the food and mixing it up. Finally, I just picked up the plate and said I'd get a new one, because I was tired of him not answering me. He very sarcastically said, "Oh, THANK YOU."
We couldn't just put it on another clean plate--he'd stirred it up so he would know if we did that, I'm pretty sure, and since the plate was "dirty" he'd have thrown a fit. So because the edges of his plate weren't perfectly spotless, we had to throw away his food and cook an entirely new meal for him.