Back in the golden age of advertising jingles, when every television commercial seemingly strove for a catchy tune that would force viewers to start involuntarily humming, most of America could sing a couplet that went, “Everybody doesn’t like something / But nobody doesn’t like Sara Lee.”

While jingles have receded in recent years, here’s one that most of America could still sing: “Everybody doesn’t like somebody / But nobody doesn’t like Betty White.”

It’s catchy. It’s also true, a fact emphatically confirmed in a new PBS special called Betty White: First Lady of Television, which airs Tuesday at 8 p.m. ET (check local listings).

This hour-long documentary includes interviews with White, a chronological recap of her career, and admiring comments from pretty much everyone she’s ever worked with who is still alive.

That last point could be an issue. When you’ve just turned 96, like White, you’ve outlived many of your peers and friends. But she still has a bottomless reservoir, including the likes of Ryan Reynolds, Tina Fey, Carl Reiner, and Valerie Bertinelli.

They represent most of the shows through which White has become a television institution, from the primitive 1950s sitcom Life With Elizabeth in the early 1950s through The Golden Girls, The Mary Tyler Moore Show and Hot in Cleveland.

They’re all comedies, which became her forte over the decades, and they showcase both her splendid timing and the Betty White persona.

To oversimplify not very much, that’s a character who is friendly, sincere, pleasant and guileless – with a twist. She uses that unthreatening innocence as a license to say startling things – occasionally a bit risqué, but mostly just funny.  

In a Golden Girls clip here, Rue McClanahan’s Blanche asks White’s Rose, “What was your first impression of me?”

With a tone no different than if she had been asked whether she bought eggs at the grocery store, Rose replies, “I thought you wore too much makeup and you were a slut.”

More recently, there was a spontaneous campaign on Facebook asking that White be invited to host an episode of Saturday Night Live. SNL knew a winner when one landed in its lap, and she became the oldest-ever host of the popular sketch show (left).

She began her monologue by admitting that before the campaign began, she had never heard of Facebook. Now that she had, she continued, “It sounds like a huge waste of time.”

It was a great line. More to the point, Betty White could say it because she was Betty White, and no one could get mad at anything Betty White said, because she was Betty White.

There’s a fascinating psychological documentary to be made on how White became America’s perpetual sweetheart when thousands of other actresses with nominally similar credentials did not.

First Lady of Television doesn’t go there. It takes White’s popularity as a premise and simply revels in it.

When White was young, during the early years of the Depression, her family moved from Illinois to California. She developed an interest in theater while attending Beverly Hills High School, though her first love was animals and she has always said she would have joined the National Forest Service had the service admitted women.

A fan of Jeanette MacDonald and Nelson Eddy musicals, she trained in all aspects of stage performance, from singing to sketch comedy. While she struck out when she tried to break into the movies, she had considerable success on radio. When Los Angeles radio host Al Jarvis decided to take his morning show to the newfangled medium of television, he hired White as a sidekick.

For four years, the show aired live for five and a half hours, six days a week. White did some of everything while picking up a solid grounding in performance timing.

She was then recruited for Life With Elizabeth, her own live talk show, and other productions. By the early 1960s, she had become a familiar TV personality, co-hosting the Tournament of Roses telecast every year and appearing as a regular guest on shows like Password – whose host, Allen Ludden (right), she married in 1963.

She was in her 50s when she fell into her serious sitcom years. Who said there are no second acts in American lives?

First Lady of Television, directed and produced by Steven J. Boettcher, suggests that over 80 years in showbiz, White never broke character. Equally rare and remarkable, she has never given anyone a reason not to like her.

After a closing shot of White sharing a snack with a real-life bear, no one is going to start now.