When you offer criticism, be aware of whom you are criticizing, how you are delivering it and how they might receive it.

A number of years ago, my son David was entering his senior year at Stanford University and decided to spend his last college summer freewheeling in San Francisco, working as a waiter. He figured he would earn enough money to really enjoy his leisure hours. He interviewed at a swanky brand-new restaurant called Stars, being opened by renowned chef Jeremiah Tower. Stars was a posh restaurant, catering to San Francisco's elite.

David figured that what he lacked in experience, he could make up in enthusiasm and education. He got the job and started training a few days later surrounded by experienced, sophisticated servers twice his age with resumes at some of the best restaurants in the country. After three weeks of intensive training, the restaurant opened.

Things were going great and David was rewarded with generous tips. One night alone, he made more than a month's rent. That same night, the headwaiter pointed out a classic service error to my son: failing to clear unused glassware. If someone wasn't drinking wine or water, their glasses should be removed from the table. David told me this was like finding a needle in a haystack, considering that each place setting had three glasses even before anyone sat down — add cocktails and a table of six would start out with 24 crystal glasses.

After about a week, my wife and I came to town and decided to check out the restaurant and let David experience it from the other side, as a customer.

My wife, Carol Ann, who has her master's in cooking and a doctorate in ordering, got the ball rolling with five questions regarding the menu selections. It seemed like we ordered almost everything. Carol Ann pointed out to us that the dressing on the salad was particularly oily, with much less vinegar than normal vinaigrette. When the entrees came, the food was not very hot, tepid at best. Everything was edible, but not spectacular. My veal stew was particularly bland.

The next day at work, David went right up to Jeremiah Tower and described the little experiment he had done. First off, he asked about the "oily salad dressing." The chef explained that he thought that a heavy vinegar dressing was too hard on the palate, too early in the meal

"Great, great!" David said, "This will be very helpful to know as a front waiter."

As Tower turned to leave, David continued, "One more thing. … The food wasn't very hot. Are you concerned that people might burn their tongues?"

"What?" exclaimed Tower. "The food should be piping hot, and it's your job as a server to get it out there quickly!"

"Yes, sir, you got it. I will," David said. So now he's thinking he is two for two in valuable, practical observations.

The chef again turned to leave, but David stopped him. "One more thing. About the veal stew. … I found it somewhat bland." At this point, Tower looked David in the eye, then spun on his heels and marched into the kitchen.

David's shift that night went well — 20 percent in tips from seemingly very satisfied customers. At the end of the night, the headwaiter mentioned that twice that evening he had failed to clear glassware. He was fired.

David was crushed. As he was walking to the cable car, he heard the headwaiter shout out his name as he jogged up to him. He looked upset and quietly said, "David, it wasn't the glassware. Next time, just be careful what you say to the head chef."

Mackay's Moral: Never tell a mother her baby is ugly.

Harvey Mackay is a Minneapolis businessman. Contact him at 612-378-6202 or e-mail harvey@mackay.com.