It was the anything-goes disco era, and OJ Simpson and Nicole Brown couldn’t get enough of Gotham’s roaring party scene.

The tall, handsome NFL star turned actor and his shapely blonde gal pal were regulars at smoldering discos like Xenon, the Limelight and Danceteria, where Madonna sang her way to stardom and the Rolling Stones celebrated the release of their LP Emotional Rescue.

And whether dancing, chatting or just canoodling at the trendy nightspots, the couple was always smiling, exchanging loving looks and whispering in each other’s ears, say the photographers who chronicled their blossoming relationship in newly emerged photos.

“They seemed to be a very cheery, happy, loving couple,” said Hal Goldenberg, one of four shooters who shared their memories of OJ and Nicole with The Post.

And if Simpson was tortured by some inner demon that would later lead him to savagely murder his wife, he didn’t show any signs at the time.

“There was no indication of what evil lurked behind the smiling face of OJ Simpson,” said Dave McGough, another of the paparazzi who shared his story.

The still-married Simpson met Nicole, then 18, in 1977 while the stunner was working as a waitress at The Daisy — an exclusive members-only disco in Beverly Hills.

Opened in 1962, it was a place “where actresses in skin tight pants would dance the Watusi jerking elbows and hips with Steve McQueen or Robert Redford,” according to Alison Martino’s blog “Vintage Los Angeles.”

By the time Simpson and the young Nicole Brown hooked up, the Hustle had replaced the Watusi.

And they basked in the adulation, showing up just about anywhere as long as there was a party and plenty of paparazzi to capture their comings and goings— which Simpson would even help stage to make sure the photogs got their best shots.

So Goldenberg, McGough and their fellow New York shooter Adam Scull got to know the couple well and shared their take on Juice — as he liked to be called, even by them — and Nicole, whom he married in 1985 after divorcing his wife, Marguerite, several years earlier.

“If he was hiding something back then, he had a great poker face,” said Scull, who shot the celebrity couple dozens of times for The Post.

“The weird thing is, I’m a New Yorker and I’ve seen it all — but he bamboozled me. Outwardly they were as lovey-dovey and as sweet and entertaining as you could imagine,” he said.

“I can tell you he was the nicest guy over the years. I photographed him in LA and New York and he was always really personable and friendly to all the photographers. He went out of his way to be nice to everybody,” added McGough.

McGough said OJ appreciated that they had a job to do and went out of his way to cooperate — which would of course increase his chances for more publicity to help quench his insatiable hunger for attention.

“He was a celebrity and very happy to be a celebrity. I think he knew the importance of photographers and getting his picture into the papers,” he said. “OJ was a regular, he’d pull up in a Rolls Royce, we loved him.”

He wasn’t above clowning around for the camera either, according to photographer, Joe DeMaria, who once shot OJ after he grabbed a security guard’s cap, holster and revolver and mugged for the camera.

“In one shot he’s pretending he’s committing suicide with the gun to his head. In another, he’s pointing at me!” DeMaria recalled.

McGough was also a big fan of the former Nicole Brown.

“His wife was lovely, really very sweet. I got to talk to her a few times, she was a very nice person,” he recalled.

But beneath that superficial image of domestic bliss lurked the monster charged with brutally knifing Nicole and her friend Ron Goldman in June 1994 in her Brentwood home.

Juice was cleared after the circus-like televised criminal trial but later found civilly liable for Goldman’s death and for battering Nicole.

He was later busted anew in a bizarre case in which he and several accomplices broke into a Vegas hotel room, held the occupants against their will, supposedly to retrieve stolen sports memorabilia.

He was sentenced in 2008 to 33 years in a Nevada prison, but is now eligible for parole as early as 2017.

Goldenberg, who considers himself something of an amateur shrink, was amazed in hindsight that he had been so easily fooled.

“I would look people in the eye, and the eye is the mirror of the soul, I’d look in their eyes, watch their mannerisms, their actions, and I didn’t catch anything,” the veteran shutterbug added.