I admit it, I've been rude while dining at a restaurant. But I have an excuse: growing up in a small town as a teenager made me unprepared for the strange things I would see when I moved to the big city. My brother BJ and his wife Jen eat out a lot, and we've seen (and/or done) just about all of these faux pas:
1. Honor the reservation
BJ thinks there should be a death penalty for diners that "no show", particularly for large parties on busy nights.
2. Manners, manners, manners
Just like your mom taught you: no elbows on the table, polite reserved conversation topics, and chew with your mouth closed. If you disgust your fellow diners (or worse, a *date* who is across the table) during your meal, maybe you should eat in your car.
3. Treat others like you would like to be treated
I once went out to a business lunch with my new boss. She was incredibly rude to the wait staff, correcting their French pronunciation of various menu items (incorrectly... she insisted the vichyssoise soup was pronounced "vish-e-swazz-E"), berated them for small details, and generally made an arrogant ass of herself. I quit the job month later, knowing she'd probably start to treat me the same way.
4. Hold your liquor
Do I get drunk and hit on you at your place of work? Why would you treat anybody any differently? No, the beautiful blonde waitress doesn't think you're cute, and even if she did, there are more tactful ways of approaching her (hint, sit at the bar, tip generously, and ask the bartender if you even have a chance with her)
5. I am not your slave
I am here to give you a pleasant dining experience. I'm not here to be the target of your pent-up aggression. If you have "issues" after a long hard day at the office, go see a shrink.
6. You *can* use a cellphone
Cell phones aren't the problem, it's boorish behavior. First of all, you may not be able to hear the call over loud restaurant ambience. So, if you can put off calling, do so. Or consider "stepping out of a moment" (and I don't mean the bathroom... people in there don't want to hear a loud conversation either). But if you must call or answer, make it short, don't talk any louder than you would to a person sitting across from you, no vulgarity, and don't use one of those geeky headsets. That's not really a dining error, just a fashion mistake.
7. You've got to be better than your kids
Taking a child out to dinner can be tricky. Even experienced parents have trouble with it. So good luck. Make things easier on *yourself*, go to a family restaurant with a boisterous atmosphere, games for the kids, and food that they like to eat. Don't try this at an intimate romantic get-away. And go with a friend or partner - whatever it takes for the number of adults to be greater than the number of kids. I know you want to enjoy your meal, too, but sometimes you have to take a fussy child outside, entertain others, and bribe the rest. You may have your "meal interrupted"... don't sit there looking like a scared cow while your child cries and cries.
See also my "Rules for Restaurants"... the flip side of the two it takes to tango.