Beyoncé does it. So do Katy Perry, Janet Jackson and Justin Bieber. Even Dolly Parton does it. But nobody does it better than Britney Spears.

She is the poster child for lip syncing. If you see her in concert in Las Vegas, she'll dazzle you with her production — the dancing, the costumes, the sets. It's just that she's not singing live. Ever.

That doesn't stop fans from flocking to her residency at Planet Hollywood.

Younger fans — millennials and Xennials (a so-called "micro-generation" born in the late '70s and early '80s) — don't seem to mind. Honestly. They just want to be entertained.

Baby boomers and Gen Xers do care. Singing live matters.

Real singers care, too.

Unless it's Dolly Parton. I outed her for lip syncing in 2004 at Xcel Energy Center. At the time, it seemed unfathomable that the country legend with that sweet, flutter-like-a-butterfly mountain-girl voice was faking it on some songs.

My review even drew the attention of the National Enquirer, which quoted my piece and even got Dolly to admit in an interview that some of her vocals were as much of an illusion as her hair.

Some people in the music industry have higher standards. Such as the Grammy Awards.

"I'm against it," longtime Grammys TV executive producer Ken Ehrlich said of lip syncing. "It's very rare on the Grammys. On the Grammys, everyone sings live — except for Milli Vanilli."

Ah, Milli Vanilli, the only act to have a Grammy taken away because they weren't a real recording act. They were two good-looking actors who fronted for anonymous studio denizens who actually did the singing that led to a 1990 Grammy for best new artist.

Not uncommon on TV

Lip syncing is not uncommon on TV. It was the M.O. back in the day on "American Bandstand," "Solid Gold" and other programs. In more recent years, some singers have resorted to lip syncing on television for various reasons — they're doing complicated choreography, they're performing outside in iffy weather or they're simply not very good at singing live.

You might recall some of the incidents such as Ashlee Simpson's lip syncing on "Saturday Night Live" in 2004 when NBC technicians played the vocals for the wrong song as she was faking it. There was Mariah Carey's faux pas on the most recent "Dick Clark's New Year's Rockin' Eve" when she wasn't able to hear the recorded background music in her ear monitors, so she stopped singing but the recorded vocals continued. This caused major embarrassment for one of the more highly regarded voices of her generation.

Carey didn't fool us. But one of our greatest singers did. Whitney Houston was lip syncing in front of millions and we didn't know it when she did "The Star-Spangled Banner" at the Super Bowl in 1991. The NFL chose a recorded version because "there were too many risks to do it live." Diana Ross, Barry Manilow and Neil Diamond also have "sung" to their prerecorded versions of the national anthem at big sporting events.

If you're old-school, you believe in singing on principle. During Grammy Week last month in Los Angeles, I interviewed nearly two dozen performers about lip syncing. Veterans over 40 such as Barry Gibb of the Bee Gees and Ray Parker Jr. favored real singing. Even the guys in Kiss, who perform in heavy costumes and tons of makeup, insist on keeping it real.

"Whenever I hear anyone say they lip sync because they can't sing and dance at the same time, it usually means they can't sing," Kiss singer Paul Stanley opined. "It didn't stop the Temptations, it didn't stop the Four Tops, it didn't stop Prince. Sometimes when talent is in short supply, lip syncing comes into play."

Everyone knows Paula Abdul can dance, but can she sing? When asked if she'll be lip syncing on tour this summer with New Kids on the Block and Boyz II Men, she was evasive.

"My hat's off to people who are able to incorporate both. It's one thing to stand and sing, and it's another thing to be physical," said Abdul, who acknowledged she was going into training for the tour. "I'm going to work my butt off cardiovascularly so I can rise to the challenge."

Age of acceptance

Lip syncing might be the live-music equivalent of fake news. Lip syncing is not about live music. It's more about theater, giving the exact same show night after night. Don't music lovers want concerts to be in-the-moment experiences with all the spontaneity that might entail?

"When you're paying to hear the live experience, there's the excitement of not knowing how something's going to go," said Kiss' Stanley. "You're not looking for perfection. You're looking for sweat, you're looking for somebody who's inspired, not somebody who's hiding behind prerecorded vocals."

Paul Shaffer, 67, the longtime David Letterman bandleader who is taking his own band on tour this year, agreed. "I don't buy it," he said of lip syncing. "People from my generation felt you've got to perform live. Kids don't seem to care. They care more about fidelity to the original record."

Barry Gibb, 70, he of the distinctive quivering voice of the Bee Gees, is succinct: "I will not lip sync to anything. Play live — or go to bed."

Some newer voices such as the Grammy-nominated soul trio King — featuring 30-year-old Minnesota-bred twins Amber and Paris Strother — take pride in singing live. But they're cool with artists lip syncing.

"There are a lot of performers, they're dancing, acting or on a trampoline or swinging from a trapeze or something," Paris Strother said. "Lip syncing, it's also an art form. It's a performing art. I have compassion and understanding for it."

Same goes for Aloe Blacc, 38, the voice behind Avicii's hit "Wake Me Up" and his own "The Man." He said that singing is important but that a great performance is paramount.

"When it's possible, you should always sing your songs," he said. "At the end of the day, you want a great performance. If it's for television and it's too cold or if there's not enough time for production [rehearsal], you want to see a great performance. I don't think people really care if it's live or not."

Many young people just want to see a famous star in person. They're happy enough to be in the presence of celebrity and watch the replication of a music video's excitement. They'd probably prefer the thrill of a selfie with a rock star over hearing her or him sing live.

Even the high and mighty Grammys will sometimes, though rarely, sacrifice celebrity over singing. Take Spears.

In 2000, I attended a rehearsal for the Grammys while doing a story on Twin Cities audio engineer Rob (Cubby) Colby, who was in charge of the sound in Staples Center, where the Grammys were being held. During rehearsals, Spears' live voice — she was singing along with a recorded version of her voice — wasn't loud enough for the arena or the TV truck engineers.

After Colby huddled with Spears' personal tour sound man, it was determined that the Grammys would rely on a recorded version of Spears' voice because, while dancing, she was not singing loud enough to be heard. And that's pretty much what Spears does in concert. In other words, she lip syncs.