Since people are comparing Johnny Carson of different eras and what made him funny, I thought I'd link this piece that I found insightful. I agree with most of the author's opinions.
http://slate.msn.com/id/2112604/
Johnny Carson
The naughty genius of late night.
By David Edelstein
Posted Monday, Jan. 24, 2005, at 3:44 PM PT
Sometimes it's easier to begin an appreciation by saying what a person emphatically was not. Consider this passage about Johnny Carson from an editorial in USA Today, which is wrongheaded on nearly every count:
But what made Carson so unusual wasn't just his success, but how he achieved it. His monologues were not biting or cynical, as is often the case with today's TV. His conversations with guests put the focus on the interviewee, not the interviewer. He didn't win laughs at the expense of others, like Jay Leno does in his "Jaywalking" segment, which shows people unable to answer easy questions. If anyone was the butt of Carson's humor, it was Carson himself
You'd think that Carson was some sort of egoless saint of television, when at his peak he was precisely the opposite—which is why, of course, so many millions of us watched him so faithfully and took the news of his passing, at age 79 from emphysema, so hard.
When Carson succeeded Steve Allen and Jack Paar as host of NBC's the Tonight Show, the shift in tone was radical. Although Allen was underappreciated as a satirist, he had a fundamentally earnest presence, and Paar was, if anything, overearnest (to the point of bathos). But Carson was cutting: There was always a chill behind the twinkle. If he cultivated the look of a boyish Midwesterner (he certainly played up his Nebraska roots), he could turn into a bad boy (or a smutty-minded boy) in an instant. He did not wear his derision as openly as his protégé, David Letterman: Carson perfected the art of taking down a guest with a sidelong look or a raised eyebrow. The reason his approbation was so treasured was because it was so hard to win.
Carson also perfected the art of making a joke that bombs even funnier than a joke that works—a mixed legacy, insofar as many modern TV hosts (among them Letterman) are more comfortable than they should be going out with second-rate material. Why was that talent so breathtaking? Because TV seemed a more earnest medium back then, too, and Carson introduced an exhilarating note of self-consciousness. In a late-'70s profile in The New Yorker, Kenneth Tynan noted that Carson could spot the flaw in his own delivery before a joke had even left his mouth. He had the fastest and most exquisite audience-reaction meter of any modern comedian: He knew when a bit had bombed so badly that it could only be salvaged by insulting the audience; when it had just missed and could be goosed into working; and when it had killed and could be ridden triumphantly into shore. (The only current host with the speed and agility of Carson in his prime is Jon Stewart, who goes politically where Carson feared to tread.)
Last year, I saw Carson in a new light when I attended a Las Vegas skeptics' conference organized by the still-amazing James "The Amazing" Randi. Many of the participants were magicians—thus affirming the century-old bond between magic and skepticism forged by Harry Houdini, who used his knowledge of misdirection to expose fake spiritualists. At one point, Randi held up a $100,000 check for his foundation from Carson, along with a note that read, "The enclosed is to help you educate Larry King and Montel Williams." (Randi sent a thank-you telegram pointing out that the amount was nowhere near sufficient.) Carson began his career as a magician, and he and Randi had once worked together to ensure that Uri Geller—who insisted that he was a genuine psychic instead of just a skilled trickster—would have a tougher time getting away with his usual flimflam. (Geller's subsequent failure to "perceive" anything on Carson's program was the beginning of the end of his superstardom.)
Carson's background in magic (and its attendant skepticism) might be one of the keys to his greatness as a comedian and talk-show host. You can see it in his focus, his economy of gesture, his heightened awareness of the audience, his skill at direction and misdirection, his easy patter, his impatience with (and malice toward) grandiosity or cant, and his essential humility—which allowed him to see through himself the way he saw through his guests. He knew how easy it was to manipulate an audience; and, like Randi, he never allowed himself to be deluded into thinking he was Uri Geller. Although he did give a platform to harmless, unpretentious nightclub psychics like Kreskin, his real view of the profession can be discerned in one of his finest comic creations, Karnak the Magnificent.
There was a downside to his magic background, too. Famously aloof off-camera, Carson couldn't relax and have a simple conversation. He set the pace of an interview, and if the guest couldn't keep up, he usually didn't slow down or help them along. (He made a show of deference only when dealing with guests who were very old, very young, or had four or more legs.) Carson saw himself as an entertainer and was stubbornly averse to (or threatened by) the exchange of ideas on television. It was his rival at ABC, the Midwestern Yalie Dick Cavett, who threw himself into the fractious counterculture of the '60s and early '70s—who interviewed essayists, critics, rock stars, and outspoken activists. Cavett's instincts as a magician were nowhere near as sharp as Carson's (they weren't even in the same dimension), but Cavett risked so much more.
It's deeply depressing that most of Carson's liveliest shows—the ones from New York, when he had dark hair and was still drinking heavily—were destroyed by NBC, back in the days before DVD boxed sets (or syndicated reruns). The program changed when the Tonight Show moved to L.A., but at least its host kept his attack for another 15 years. The later Carson, the Carson of 1981 until his retirement in 1991, was a subtly different presence. The rituals were all the same—the theme song, the golf swing, the banter with gaudy bandleader Doc Severinson ("You look like Liberace's lawn ornament"), the reflexive chortles of courtier Ed McMahon. But Carson had become softer, more detached, and more blandly genial—at least in comparison with his old knife-edged self, or with Letterman, whose bracing NBC show he helped to produce. You could see him decide not to go for the big comeback, to let the joke slide, to nod and make some meaningless noises of agreement.
That might have been the Johnny Carson that the USA Today editorialist remembered, but it was not the brilliant, scathing imp masquerading as Mr. Middle America who changed comedy—and television—forever.