According to USA Today, CEOs of all types and sizes (at least 12 of them, anyway) agree: People who are rude to wait staff at restaurants are, well... assholes:
... it seems to be one of those rare laws of the land that every CEO learns on the way up. It's hard to get a dozen CEOs to agree about anything, but all interviewed agree with the Waiter Rule... How others treat the CEO says nothing, they say. But how others treat the waiter is like a magical window into the soul. And beware of anyone who pulls out the power card to say something like, "I could buy this place and fire you," or "I know the owner and I could have you fired." Those who say such things have revealed more about their character than about their wealth and power.
Somewhere a large publishing house in New York, there's an editor thinking, "there's probably an entire business book that could be written around this brilliant piece of business insight." Look for it in Fall of '08.
But they miss a critical demographic that's an exception to the Waiter Rule: the people who are supremely nice to the people at the very top (the CEO, the Executive VP, the largest donor, etc.) and supremely nice to the people they perceive to be at the bottom of the food chain (the administrative assistant, the doorman, the waiter, etc.,) and complete jerks to everyone in between. Deference to the first demographic is expected; deference to the second reinforces their self-perceived egalitarian, class-agnostic liberalism. And the last demographic is simply invisible to the naked eye of the Walking Exception to the Waiter Rule.
CEOs Say How You Treat a Waiter Can Predict a Lot About Character [USA Today]
Related: You Say It Best When You Say Nothing At All