The party, in a triplex loft floating high above the East River, was just getting started a little after 6 p.m. on Wednesday. The models, leggy young women dressed in Nina Ricci, Proenza Schouler and Calvin Klein, had started to circulate as waiters came through with trays of canapés like smoked salmon topped with glistening orange roe. A jazz quartet kept up a steady rhythm from under the stairs as guests milled about, exclaiming over the panoramic views through four enormous, synchronized glass clocks set in the tower walls.

But over by the door, the evening’s hostesses were tied in a vibrating knot of anxiety, trailed by a television crew as they paced in heels with phones glued to their ears and fretted about the rain. They were real estate agents trying to drum up excitement for what could become the most expensive apartment in all of Brooklyn — if it sells at the right price — and frantically working to arrange cars to ferry missing brokers over to Dumbo from Manhattan.

“It’s very hard to get people here just to look at it — they won’t come,” said Michele Kleier of Gumley Haft Kleier, which is marketing the 6,800-square-foot apartment at the top of the ClockTower building at 1 Main Street. “But if you offer them a fabulous evening,” she added, and provide transportation, maybe you can get enough people who know other people willing to shell out $23.5 million for a trophy apartment, with its own glass-walled elevator, crow’s nest deck and catering-inspired kitchen.

But the party, an event that has become almost de rigueur as a luxury marketing tool, was notable for more than the lengths to which Ms. Kleier and her daughters, executive vice presidents of her agency, had gone. It was also an embodiment of the intersection of real estate and reality TV, a junction where the proliferation of shows turning a voyeuristic eye on the gaining and shedding of expensive homes has injected a higher dose of showmanship into the marketing strategy.

Indeed, the ClockTower party, taped for the half-hour series the agency regularly is featured on, HGTV’s “Selling New York,” became an art-and-commerce version of the serpent eating its tail. Asher Abehsera, managing director for residential properties at Two Trees, which developed the building and much of Dumbo, said he had been impressed by a segment on the show featuring Ms. Kleier’s marketing of the Stanhope on Fifth Avenue and asked her to take on the ClockTower, which went on the market in 2009 for $25 million.

“Very successful brokers are really about selling real estate, and it’s very much all day, all night — it’s part of what they do,” said Shari Levine, senior vice president for production at Bravo, which is shooting another reality series, a New York version of its Los Angeles-based “Million Dollar Listing,” which will follow the work and personal lives of three brokers.

“Selling New York” follows a revolving groups of brokers from three agencies. The brokers are paid honorariums for their appearances, enough for “a decent dinner” out, said Courtney Campbell, who oversees the program at JV Productions, the company that took it to HGTV.

But Ms. Kleier and her daughters, Sabrina Kleier-Morgenstern and Samantha Kleier-Forbes, say it has brought them clients.

Frederick Peters, president of Warburg Realty Partnership, who also appears in the series, sees the benefits differently.

“It would be hard for me to say that we now have more listings because of that,” he said. “But inevitably, over time, having more people know about your company and see that we do a thorough and professional job translates into more calls, more business.”

But some in the business see no benefit at all, and caution that many of the so-called new clients are actually more interested in being on television than in buying or selling property.

“I think it is much more about someone — whether it’s a buyer, a seller or a broker on there — about their 15 minutes of fame than anything else,” said Hall F. Willkie, president of Brown Harris Stevens, adding that buyers at the highest end want more, rather than less, privacy about their interests and purchases.

Mr. Willkie said the shows reached a vast audience, but not an audience of buyers. “No one looking for real estate in New York City — not a soul — turns on reality TV to find their property,” he said.

Back at the party, though, things had picked up. A mix of brokers, publicists, business professionals and artistic types, like the clothing designer Yeohlee Teng and her partner, the architect Joerg Schwartz, were crowded onto the main level and wandering upstairs. Andrew Rothstein, one of the “Selling New York” directors, hovered behind the cameras, listening through an earpiece to what the Kleier women were saying as they squired guests around.

“We’re looking to capture real moments, real stuff,” he said. “Someone could come up and say, ‘I want to make an offer.’ We want to know right away. Then we want to grab and interview them.”

A few feet away, a man resembling a slighter version of the rapper Fat Joe — who identified himself as Pablo Escobar Jr., though the family of the slain drug lord has labeled him a fraud — took in the view, one he said made the price “not bad,” along with his companions. They included Brittany Andrews, a former adult film actress — “I’m a two-time Hall of Fame porn star!” she volunteered — who said she now made mainstream movies and was considering the space as a film location. Later the group attracted attention as they posed for pictures with Richard Garcia, a Tupac Shakur impersonator.

At the end of the night, as the caterers loaded glassware into pink plastic racks and the models had changed out of their designer garb from Edit boutique on the Upper East Side, the Kleiers seemed to be breathing a collective sigh of relief.

“It was horrible weather; I was so nervous when I first got here because I was like, where are the people? Now it’s packed,” Michele Kleier said. “The party is over, and nobody’s leaving. There are still people here, so yes, I’m happy.”

She paused. “I’ll be happier when I sell it.”

- Kirsten Luce, New York Times