Thinking of throwing a tantrum the next time things don't go your way when you travel? Consider this before you do.

Gary Zeune overheard the passenger in front of him curse at a Southwest Airlines ticket agent in Columbus, Ohio.

The agent politely asked him to calm down, assured him that profanity wouldn't get him on the flight he wanted, and offered to add him to a standby list. The passenger got angrier, unleashing another torrent of salty language.

"The ticket agent asked him for his credit card," Zeune remembers. "And he gets a big smile, thinking he's going to get on the flight. Then she says, 'Sir, you're not flying Southwest today. Go fly someone else.' And she refunds his money."

After last week's column about travelers who get special treatment for good behavior, you might conclude that rudeness would always result in some form of punishment. But the truth is complicated.

Yes, in an ideal world, every obnoxious hotel guest would be shown the door, every boorish passenger sent packing.

But not in this world.

Zeune's story is the exception, not the rule. At a time like this, when the travel business is hitting rock bottom, bad behavior can be a means to an end. There's a difference between a polite but firm request and a shrill demand, of course. Where's the line? Here are five things you should never do when you travel, at least according to these veteran travelers:

1. Threaten violence

Valerie Lockwood, a sales coordinator for a hotel company in Plymouth, Minn., remembers one customer who broke two chairs, a sofa bed and left cigarette burns in the furniture in his nonsmoking room. When he checked out, she told him the hotel would keep his $100 deposit.

"He flipped out and threatened to beat and kill me," she says. The police had to be called, and the angry guest was fined $500. He should have just paid the $100 and left quietly.

2. Yell

Niyati Chheda, a higher-education consultant in Chicago, was standing in line at the airport recently when a family cut in line. She pointed out that there was a line, which set the mother off.

"The lady kept screaming at the top of her voice at how we didn't understand it is difficult to travel with kids, and she used some very abusive language," Chheda remembers. "I understand she may have not noticed the queue and it was an oversight. In such a situation, one would apologize, at the very least. They were, however, far from that."

The family was sent to the end of the line.

3. Have one too many

Alcohol and travel don't mix. That's true if you're driving, and almost always true when you're flying.

When Allison Hughes was flying from Orlando to St. Louis with her family, she witnessed a loud argument between a gate agent and a drunken passenger. "Very, very, drunk," she recalls.

At issue was the agent's refusal to allow the passenger to board, presumably because of her inebriated condition. "She kept saying that she needed to get to Houston that night because her husband was going to pick her up, and she couldn't miss the pickup. When the gate agent offered her a later flight, she began yelling all sorts of expletives and swinging her arms wildly," she says.

Result? The agent called airport security, and the passenger was escorted from the gate.

4. Leave your manners at home

Somehow, travelers think the rules don't apply when they're away. You see that a lot with elite-level frequent fliers who believe they have a license to misbehave.

Candace Quinn, an executive consultant who lives in Washington, watched such a traveler hurry through the TSA screening area at Chicago's O'Hare airport recently.

"She shoved into me," Quinn remembers. "She told me to hurry up, that she was late." That got the attention of a TSA officer, who didn't approve. "So she had her walk through a couple times. I felt somewhat vindicated," Quinn adds.

5. Act like a jerk

You've met jerks elsewhere, but being trapped on a plane, train or bus with them can be intolerable, because you can't walk away.

David Bowers, who works for a law school in San Diego, was boarding a Swiss flight from Zurich to Atlanta when he witnessed an altercation between a young woman sitting in a bulkhead-row seat and a businessman who had the same seat assignment. "He went ballistic, blocking boarding for others and demanding that a flight attendant give him his reserved seat," Bowers remembers. The attendant did — after moving the young woman to business class.



Christopher Elliott is the ombudsman for National Geographic Traveler magazine. You can read more travel tips on his blog, elliott.org or e-mail him at celliott@ngs.org.