Restaurant insiders from across the US have revealed what really goes on behind customers’ backs.

Tricks, such as adding extra sugar to kids’ meals so children enjoy them more, and that a daily “special” is often leftover ingredients that need to be used up, were revealed in the list of industry secrets compiled for Good Morning America by Reader’s Digest.

The mostly-anonymous group of wait staff also admitted some common lies told to customers.

One revealed that they would tell a vegetarian that a dish contained no meat stock, regardless of whether it did or not, just to sell the dish.

And a Kansas City waitress said that she will just serve decaf coffee after 8pm so she only has to clean one pot at the end of the night – but will confidently tell a customer that their coffee is caffeinated regardless.

“I’ll bring out a tray with 12 coffees on it and give some to the customers who ordered regular, others to the ones who ordered decaf. But they’re all decaf,” she admitted.

As for milk, they reveal very few outlets beyond Starbucks carry skimmed milk, and your skinny latte has most likely been made with 2% or whole milk instead because “it’s just not practical” to stock so many varieties.

Restaurant insiders from across the US have revealed what really goes on behind customers' backs

Even the most upscale breakfast buffets are not immune from shortcuts, with another revealing that “99 times out of 100” scrambled eggs are made with a powder instead of fresh eggs.

Kids’ meals are a shady area too: a waitress at a well-known pizza chain admitted: “We put sugar in our kids’ meals so kids will like them more. Seriously. We even put extra sugar in the dough for the kids’ pizzas.”

Some trade secrets are so offputting, it affects how wait staff order when they dine out themselves.

One waitress told Reader’s Digest that she would never have a lemon slice in her drink, having seen that the fruit are rarely washed before being sliced and handled by many different staff before they make it into a customer’s drink.

Another revealed that they would never order fish if dining on a Sunday or a Monday because a restaurant’s seafood deliveries usually come just twice a week so the freshest fish is most likely served between Tuesday and Friday.

The list also delves into the type of customer behaviour that servers respond to best – and in that, provide the best quality service.

First dates, especially blind dates, one Michigan waiter said, are great for tips because a guy will typically show off by ordering wine, and leave a generous 20-25% tip.

But diners can quickly lose favor with their waiter by doing something as simple as ordering hot tea – apparently the most annoying menu item to prepare.

“The single greatest way to get your waiter to hate you? Ask for hot tea,” a New York maître d’hôtel told the magazine.

“For some reason, an industry that’s managed to streamline everything else hasn’t been able to streamline that. You’ve got to get a pot, boil the water, get the lemons, get the honey, bring a cup and spoon. It’s a lot of work for little reward.”

This is not the first time that restaurant staff has lifted the lid on what goes on behind the scenes. Last month social news website Reddit asked fast food employees for “the one menu option at your employment that you would recommend people never eat?”

Within 24 hours, the conversation generated more than 6,000 comments revealing the alleged dodgy practices in fast-food chains, including some branches of Wendy’s, McDonalds and Subway.

The thread also offers some useful tips for customers to be aware of including, mouldy ice machines and how condiment containers can be endlessly refilled without being cleaned.

Chicken nuggets and grilled chicken were repeat offenders throughout the thread. One former McDonald’s employee warned against the chicken nuggets recalling: “I accidentally left a whole bag of about 100 chicken nuggets out on a counter for way too long. They melted. Into a pool of liquid.

“I never understood why. But they were completely indiscernible as being the nuggets I once knew.”

FIVE OF THE WORST RESTAURANT RUSES:

VEGETARIAN OPTIONS: “If you’re a vegetarian and you ask if we use vegetable stock, I’m going to say yes, even if we don’t. You’ll never know the difference.”

DAILY SPECIALS: “Watch out for the soup of the day. If it contains fish or if it’s some kind of <<gumbo>>, it’s probably the stuff they’re trying to get rid of.”

FISH: “Don’t order fish on Sunday or Monday. The fish deliveries are usually twice a week, so Tuesday through Friday are great days.”

KIDS’ MEALS: “We put sugar in our kids’ meals so kids will like them more. Seriously. We even put extra sugar in the dough for the kids’ pizzas.”

HOMEMADE: “[One boss would] go to Costco and buy this gigantic carrot cake for $10 and tell us to say it’s homemade. Then he sold it for $10 a slice.”

Source: Reader’s Digest