Case in point: Recently I went out for lunch with some colleagues I’d known for years and thought were lovely people. Suddenly, we’re sitting at a restaurant table and they turn into high-maintenance princes and princesses who every five seconds all but snapped their fingers and rolled their eyes in the direction of our perfectly capable servers. I was shocked by how rude they were to the waitstaff. I had to reevaluate them totally. And goodness knows that’s the last time I’ll invite them out.

One woman I knew would avoid eye contact with the waitress, then mutter and mumble her order. It seemed so hostile. What is that about? Is it a power trip? I feel that whenever people are rude to those whom they feel are beneath them, it is so indicative of character. It’s also such hubris. When you see someone who is doing a job you wouldn’t want to do, you should simply think: There but for the grace of God go I.

Another coworker was particularly horrid on the first and last occasion I ate out with him. He saw waiters as his prey. When they came over to take his order in the middle of a conversation (which, let’s face it, is typically most of the time unless you’re giving your companion the silent treatment), he had this habit of hissing at them, “I’m speaking.”

Can you believe it? I wanted to hide under the table. Now if I need to meet with him, we do so in my office. And how could I ever recommend him for a job or anything else where he’d be dealing with other people? Who knows when this horrid “I’m-speaking” monster would emerge.

Once I learned that some friends were bad tippers, I made sure always to take the bill when dining with them. Then they would admonish me for overtipping. I would say, “It’s none of your business how much I tip.”

Of course, I don’t feel that way when the situation is reversed. When I notice someone I’m eating with is undertipping, I try to throw down an extra bill or two to make it right. But you have to be really sure they don’t catch you doing it, because it insults their (albeit totally wrong) sense of themselves as good hosts. Also, it often means you have to have a conversation about whether or not the waiters deserve that extra bill right in front of the waiters, which makes the whole exchange doubly rude.

Now to get to the karma thing: You make yourself so vulnerable by not tipping well or treating people in the service industry with respect. Not only is it wrong to treat another human being like that, but there’s a practical consideration: They’re standing between you and eating. Without waiters, nothing comes to your table, and nothing goes away. Aren’t you worried that they’ll put rat poison in your food, or at least spit in it? If I were a waiter and someone talked rudely to me, I know I would be seriously tempted. I would never intentionally put someone’s life at risk, but half-a-dozen laxative tablets dissolved in a cup of coffee would be very sweet payback, indeed.

When I watch British period movies ( Gosford Park,for example), I’m struck by how people in service are ignored to the point of invisibility. Is that what this mistreatment of waiters is about? Some kind of reverence for Mother England? We’re supposed to be a democracy in this country. We’re not supposed to have royalty. From my perspective, getting high and mighty with anyone standing behind a counter or working at a restaurant is downright un-American.

Yes, there are bad waiters. Once at dinner with my family, we had a waitperson drop an entire tray of Bloody Marys on us. My sister had on a white sweater. Her four- and one-year-olds were very upset by the noise and mess and the sudden sight of their mother covered in what looked to them like blood. The whole restaurant stopped and stared at us. And would you believe the waiter and manager didn’t even acknowledge it? They didn’t give us a discount on our bill, nor did they apologize. That’s the rare situation when I think it’s fair to tip less than the going rate.

My niece, Wallace, was in town recently, and we went out for dinner. She’s doing some teaching and loves it. We were chatting away about academia. The restaurant was crowded, so we ate at the bar. The bartender was incredibly nice, so we talked with him a bit. At the end of the night he comped our drinks because he said, “You were so nice!”

I thought about it, and we hadn’t been thatnice. We’d just been friendly and polite. I guess that’s rare enough to make him impressed. How disappointing is that?

Now that I think about it, when faced with unexpected generosity, I’m always floored. Once I was having lunch at Michael’s with Grace Mirabella when a man came up and introduced himself as Mickey Drexler. Mickey was the CEO of the Gap for many years and had just moved over to J. Crew. He said he was a big fan of the show.

“Well, I’m a big fan of what you did with the Gap,” I said, “and I can’t wait to see what you do at J. Crew.” (As we know now, he did an amazing job repositioning that brand.)

The next day, I received a handwritten card from Mickey Drexler with a 30 percent off J. Crew Friends and Family discount card for life.

I GO FOR LONG periods of time when I feel like casual politeness is completely extinct. I received an e-mail recently from a certain glamorous host of Top Chef. I won’t say who she is, but she was once married to a world-famous novelist who received death threats.

She told me she was looking for a jewelry designer for her line, and I said I would put my radar up and send her anyone I found who might be a good fit. Well, I found someone terrific, discovered she was available, and sent along her résumé. I was very proud of myself for making such a great match.

Then I never heard back. Nor did the designer. I was so embarrassed. Here I had this great jewelry designer all excited, and then it was as if I’d made up the whole gig. Either the glamorous host should have followed up with the designer about the project or written one of us back to say, “I found someone, but thank you so much.”

Without that acknowledgment, I have to assume she didn’t really want my help after all, so I’ll keep that in mind if she ever asks for anything again.

To be honest, few people will help you a first time, especially in fashion. This business is so ruthless. I hope I’m not destroying anyone’s warm and fuzzy feelings about the industry to reveal this, but many fashion designers really and truly hate one another. I think it’s because there is only a finite number of people who buy very expensive clothes, so the thinking among designers is: “They have my customer” or “That order could be mine if they weren’t here.”

Of course, plenty of people in the fashion world are wonderful. When John Bartlett, a lovely man, closed his Claiborne by John Bartlett brand, there were people saying, “It’s because he’s too nice that this happened to him.”

No! It’s the economy, among other things. The only difference between him and all the horrible divas who lost their jobs at the same time is that now everyone wants to work with John because he’s such a great guy, and no one wants to work with the others.

Certain awful people prosper in the short term, but how much fun is your life if you’re a diva everyone hates? And if bad behavior happens at the office, it almost always happens at home, too. People make excuses for divas. I don’t want an excuse. I don’t care about the reasons behind extreme misbehavior. I don’t want to sound coldhearted, but it makes me crazy when people say, “Well, X is happening to her, so of course she’s yelling at her assistant.” If X is happening to you, that should be all the more reason to keep everyone close by being kind.

To his immense credit, Michael Kors is a diplomat who takes the high road. But most designers are totally threatened by other designers. When we have two designer guest judges, you can feel the hostility in the studio. The judging is edited in such a way that you usually can’t tell, but every now and then you’ll catch a whiff of the tension. Multiply that bitchy glance by a million, and you’ll get some sense of what it’s like.