So there's a whole science of getting double tips, what we call the "thank you and thank you again." For instance, I stamp the check and smear it a little bit so you can't read that it's 15 percent gratuity. Or you might write on [the bill]'have a great trip' right over the total," Pickhardt explained.
He said sometimes unscrupulous waiters will simply write "an arbitrary total on the back that's $5 or $10 more than the actual check, and put a couple of mints on it."
The tricks are even smoother when you move over to the bar, because things happen faster there, according to Pickhardt and Collins.
"See, the bartender, he's the ground zero of scam," Collins said. "He may give you three quarters of a shot, instead of a shot and a quarter. You don't know the difference, because you didn't watch him"
"Or he might come back with a bottle of his own and fill up the top shelves with some cheap stuff that he picked up at the store," said Pickhardt.
"You make the strawberry daiquiri but you don't put any alcohol in it. You just pour a little bit of the strong stuff down the straw. They take that first whopping sip and whoa! This is a strong daiquiri. Psychologically, again, they think they got a great deal and a strong drink when in fact they got a fraction of a shot, freeing up the rest of that shot to be scammed by the bartender," said Collins.
You may also be getting shortchanged on your plate. Call it restaurant recycling.
According to Collins, some eateries will reuse bread. "The half eaten goes in the bread pudding or the stuffing box and the other loaf goes in the next person's dinner," he said.
"Or they make croutons. Everything is -- can be reusable. Nothing is thrown away in a restaurant at all, ever," said Collins.
"I would never eat salsa because I've seen buckets of salsa ... you have your salsa on the table and you dump it back in the pot and, and constantly reused," Collins.
Restaurants also reuse butter, the authors say.
And that butter, according to Bourdain, can turn up in your appetizer.
"Many restaurants save up their table butter, used table butter in a big crock of softened butter that they take out of your little, you know, butter dishes at the table. They'll heat it up, strain out the cigarette butts and the bread crumbs and use that for the hollandaise. Gross, but not unhealthy. I mean, they bring it up to a boil so it's OK," Bourdain said.
So, if your meal messes up your bon appetit should you complain? Collins said definitely not.
"One word of advice to the consumer out there: Don't ever, ever send anything back and then eat it afterward. Don't ever, ever aggravate, humiliate or in any way demean your waiter before you've gotten your food. That's a big mistake," he said. Pickhardt said he's seen all sorts of gastronomical revenge by waiters serving picky patrons -- including spitting in meals.
Brian Matzkow, who owns SAPA, a trendy restaurant in Manhattan's Chelsea district, disagreed. He said he wants to hear diners' complaints so he can make amends.
"What kills me is the quiet guest. Speak up. Tell the management. Tell the owner. They want to know if things are not right, so they can fix it. So they can make your experience enjoyable," he said.
Matzkow said the scams we learned about just don't happen here . He believes these scams have become less common because of good technology, camera systems and surveillance. And that's true at plenty other eateries too.
Both Pickhardt and Collins admit that SAPA is an unlikely spot for scamsters, and that the schemes described in their book are over-the-top, intentionally provocative, and not necessarily autobiographical.
Bottom line: Take what they say with a grain of salt, but look closely at your check; and make sure the numbers add up. Chew on their information -- with your mouth closed, of course, but your eyes wide open.