Is your restaurant spying on you?

(
)

Do you know if you’re a B.T. or a B.B.?

Well, your neighborhood restaurant might.

As for you clueless diners out there, we’ll let you in on a little secret: That’s one waiter’s shorthand for “bad tipper” and “big bitch.”

Avid diners know OpenTable as the online hub to book tables without being placed on hold. But servers, sommeliers and maitre d’s use the system to easily catalog diners’ habits and quirks, resulting in a vast database of customer information.

A client’s OpenTable profile could include his birthday, favorite cocktail or latest Yelp review. It might also list details about his personality, professional life and even his kids’ education.

“You can leave documentary notes about a customer — ‘This is the customer’s anniversary,’ ‘This is the customer’s favorite drink,’ ‘This is the customer’s favorite table.’ Or, we’d have little initials — B.T., B.B. Most of it was coded, because people would lean over the hostess stand,” explains Steve Dublanica, the former waiter behind the blog “Waiter Rant” and author of a new book about tipping called “Keep the Change,” who reportedly worked at Nyack’s Lanterna Tuscan Bistro.

Such details are only available to restaurant staffers — and vary from establishment to establishment. (Restaurants that use OpenTable can keep notes on any guest for which they have a name, regardless of whether those guests are Open-Table users.)

Are you a frequent no-show? Do you always send back food?

Chances are your less-than-stellar track record has not gone unnoticed.

“The [industry] is a lot more organized now. You have a lot more information,” says Celeste Fierro, senior vice president of The One Group, which operates trendy restaurants such as The Collective and STK in the Meatpacking District. “When a customer calls, [the OpenTable system] prints up who they are, what they like and don’t like. You can’t really put that in books and transfer it — things get lost. Now it’s automatically saved. You put in the name and it prints up a whole history of the client.”

The ability to track customers is one of OpenTable’s big perks, but it doesn’t come cheap for restaurants — which pay hundreds of dollars in setup and monthly fees, not to mention $1 per guest for every reservation booked through the system. (That fee drops to 25 cents per guest if the reservation is made via the restaurant’s own Web site.) In return, restaurants can build customer histories that either come from first-hand experience or from searching Google, Twitter and Yelp.

“Most of the time we use Google when somebody walks in and we think, ‘We know that guy. Is he someone who’s been in here before, or did I see him on last week’s episode of ‘The Bachelor’? And we’ll do that on the floor with the customer right in front of us,” explains Corry Arnold, a reservation booker at 14th Street celebrity magnet Abe & Arthur’s.

But online sleuthing isn’t done just to ensure VIPs are taken care of.

In October, the blog Gourmet Live reported an incredible incident. A man who tweeted about a Burger King meal at the Montreal airport received a surprise course of tiny lamb burgers when he dined at Danny Meyer’s four-star Eleven Madison Park the next day.

“We hope these are better than the one you had at the airport,” remarked a server. Clearly, they had read his tweets. But had the restaurant somehow crossed a line by delving too deeply?

“So much of this is about reading the guest,” says Sandra DiCapua, Eleven Madison Park’s 25-year-old maitre d’. “Is it a business dinner? Is it a celebration? What’s the vibe at the table?”

(By the way, the customer was thrilled by the experience — as was a diner who received a jar of bacon-granola after musing about the pairing on a blog.)

An avid reader of newspapers who uses Google and Twitter for information about clients, DiCapua says her research skills were inspired by a visit to the Four Seasons two years ago.

“[Four Seasons co-owner] Julian [Niccolini] has a very classic approach to people,” says DiCapua. “He knows his regulars, and does everything he can to accommodate them and to keep track of [them].”

For many restaurateurs, today’s detailed dossiers are merely a modern spin on the old-fashioned, high-touch service associated with legendary hosts such as Niccolini and Sirio Maccioni, who’s been running Midtown’s storied Le Cirque restaurant since 1974.

“A good restaurateur knows its clients,” says Steve Millington, general manager of media power haunt Michael’s, whether that’s a regular’s preference for ice-cold Sancerre or Leslie Stahl’s disdain for lemon in her Diet Coke. “You can’t rely on memory and Post-it notes.”

According to industry veterans, such sleuthing ensures that a customer feels taken care of.

“[If] Malcolm Gladwell sits down with Barry Diller,” says Millington, who uses Google and OpenTable, “I want to make him feel like, ‘Hey, not only do we know who you are, but we really think you’re an amazing author.’ ”

Similarly, when Arnold learned via Google that Knicks star Amar’e Stoudemire also hailed from Orlando, it proved an instant icebreaker.

“With old-school maitre d’s, their job [was] to know who was who and what they liked. Whether they did that in a little notebook or by collecting business cards or in their brain, I’m not really sure,” says Arnold, 28. “I know that I’m very happy to have all the tools I possibly can to keep track of these things.”

But while such data can offer important clues about customers’ moods, desires and personalities, restaurants have to be careful not to come off as creepy or, worse yet, downright offensive.

“If a guest ever reads their [OpenTable] profile, we want them to feel comfortable reading it. There shouldn’t be any information that you wouldn’t want anyone to see — from the guest to the general manager,” says DiCapua, who notes that only one client, a regular, has ever asked to see his profile. (She showed it to him: “There’s nothing [in there] he doesn’t know about himself already.”)

Arnold agrees.

“I don’t think anyone’s going to be upset that you remember what they like [or that] you remember their birthday. If companies are using this information to aid in marketing or sales, that’s when it gets a little scarier. We’re using it solely within the restaurant. We’re not calling you and saying, ‘Hey, it’s your birthday. Get in here,’ ” says Arnold.

“There’s a fine line, but as long as you don’t cross it, people just think you’re good at your job.”

But what happens if you wind up on a restaurant’s naughty list?

“It doesn’t automatically mean you’re blacklisted or hated, but it gives the waiter a warning [so that he or she] could modify [their] approach to a table,” says Dublanica. He goes on to recall denying one B.T. a window table on Valentine’s Day.

“We try to stay away from opinion and stick to facts as best as we can,” Arnold says. “But if you walk out on your bill, there’s probably not going to be such nice things written about you.”