This is strictly a stream of consciousness type thing.
1) STEMWARE: I really hate it when waiters wrap their sweaty palms around the drinking surface of wine glasses when carrying them to the tables of customers. I've trained more than a few people in wine service (I used to own a side business in private on-site bartending) and that one gets my goat every time. Stemware is supposed to be held by either the STEM, or the base ... not the bulb or the lip of the bulb !

2) BUFFET: I was raised by parents who grew up during the great depression, so I've been well trained in not wasting food. Accordingly, I really hate it when I go to a buffet, and I'll see some wasteful inconsiderate goomba shovel a massive portion onto their plate, get it back to their table, take 1 or 2 bites, decide they don't like it, and then abandon it for a massive portion of something else they havent had yet ... and the waitress dutifully lugs it away and dumps it in the trash.
3) FAUX WINE SNOBS: Speaking as an amateur winemaker, a former P/T wine steward and someone who's corked & uncorked thousands of bottles of wine over the years, I can spot a phoney "wine snob" a mile off. Case in point - It irks me when I see someone at an adjoining table, who hasn't the slightest clue what they're doing, perform a bogus "cork ritual" and/or improperly send back a bottle of wine for entirely wrong reasons. Just for posterity, let me give the uber-short version of how it should be done.
* THE CORK RITUAL: A properly trained waiter will bring the bottle to your table, display the label so that you can confirm that it's the wine you ordered, cut off the cap, and then remove the cork and hand it to you so that you can verify that (a) the cork is undamaged and (b) came from the bottle you ordered (proof against tampering - which has been known to happen with very expensive wines) ... nothing more. You can learn 95% of what you need to know just by looking at and pinching the cork. You only need to sniff it if there's signs of degredation or damage (which might be a telltale of a damaged bottle of wine) ... and that requires at least a passing familiarity of common wine problems that most lay people dont have (too much to go into here). I cant help but laugh everytime I see some noob conspicuously sniffing a brand new undamaged virgin cork from a very young bottle of wine ... hell, I've even seen noobs sniff those multi-colored plastic corks that are entirely immune to traditional cork problems (weeping, mold infection, etc.), as if doing so would somehow reveal the hidden mysteries of the universe.

* SENDING IT BACK: It's only proper to send back a vintage wine if the wine is damaged or otherwise not in good condition ... you cannot and should not send it back simply because you don't like a perfectly good and undamaged bottle of the wine you selected - you're the one who picked the wrong wine, and it's completely improper to punish the restaurant for your mistake.