The American presidency, it has been said, is the most intimate of offices. In the modern TV era, to elect a president - or even just to observe US politics from overseas - is to invite him and his family into your home for at least four years, and to learn altogether too much information about their lives. Bill Clinton's sexual activities are only the most lurid example of this; in some ways, revelations of Jimmy Carter's habit of reading Bible passages to his wife at bedtime were just as personal. Yet as the administration of George Bush reaches its final days, it's hard to escape the conclusion that even the last eight horribly eventful years haven't succeeded in revealing the character of the man. You can, of course, call him a warmonger, or a liar, or a stooge of the super-rich, or someone with reckless disregard for his compatriots faced with natural disaster. But these are labels, not descriptions of his internal life. Despite countless biographies and speculative newspaper and magazine articles, we're barely any closer to answering the question that seemed pertinent back before Florida, before 9/11, before Iraq or Katrina: what, exactly, is going on in there?

During Bush's first campaign in 2000, the consensus among many liberals was that he was an idiot, a barely literate simpleton in the Chauncey Gardiner mould. Many of the greatest Bushisms date from those early days. "Rarely is the question asked: is our children learning?" a windcheater-clad Bush noted during a campaign stop in South Carolina, a couple of weeks before inviting a New Hampshire audience to imagine themselves in the shoes of a single mother "working hard to put food on your family".

But only the steeliest critic could have denied that there was something likeable about him. His verbal gaffes, supporters explained, were part of that appeal: he was a regular American, not a Washington egghead; his intelligence was not intellectual but practical and interpersonal. If you mocked when you heard him speculate about the effects of the merger of Time Warner with AOL - "Will the highways to the internet become more few?" - that said more about you than it did about him, and what it said was that you were snobbish and out of touch. This was propaganda, of course. But then again, you try watching Journeys With George, Alexandra Pelosi's documentary on the 2000 campaign, without being slightly charmed as the candidate jogs up and down the press bus, demonstrating the talking-fish toy Big Mouth Billy Bass with authentic excitement.

Nobody tries to use Bush's gaffes to defend him these days, of course; not many people try to defend him at all. And the interesting thing was that, as his presidency conclusively unravelled, Bush got much better at avoiding the more superficial embarrassments: he largely stopped jumbling his words, walking into doors, or raving to journalists about the "unbelievable" White House dessert menu. ("Yesterday... we had this, I'm not even sure, coffee ice-cream, surrounded by this unbelievable meringue, beautiful meringue," he's quoted as saying in Frank Bruni's well titled campaign memoir, Ambling Into History.)

In view of the loss of life in Iraq and Afghanistan, there are those who will argue that it's tasteless to dwell on the Bush presidency as comic turn - that it grants him too much to acknowledge his contribution to the gaiety of the planet, given the size of his contribution to its troubles. But the comedy and tragedy of the Bush years are inextricably bound together. The shudder with which we'll remember them expresses both horror and laughter, and the laughter is important for staying sane. Amid weightier matters, future historians will surely wish to record the following highlights of the outgoing president's comic legacy.

The slapstick comedy

If you'd wanted to invent a story to make Bush look foolish, you might have spun a tale of him choking on a pretzel while watching a football game, blacking out, injuring himself, and waking to find his dogs Spot and Barney fussing over him in concern. But it happened, of course, as did the moment in Beijing in 2005 when he strode from a press conference directly into a locked door. (What's interesting is not so much the incident itself, which was the fault of his handlers, but the frozen, baffled smirk that fixes itself on his face as he realises he's going to have to generate an alternative course of action in order to leave the room.) Like many others, the incident seemed planned so as to hand easy one-liners to late-night television hosts - in this case, jokes about Bush's lack of an exit strategy.

The inexplicable moments of pedantry

His own verbal infelicities notwithstanding, Bush could be strikingly petty about the slip-ups of others, and never more so than during the first presidential debate of the 2004 election campaign, when John Kerry mocked the notion that Bush had invaded Iraq with a grand coalition of global support. "When we went in," Kerry said, "there were three countries: Great Britain, Australia, and the United States. That's not a grand coalition. We can do better." It's almost possible to take pleasure in Bush's delight as it dawns on him that Kerry has made an error. "He forgot Poland!" the incumbent president crows, as if that made all the difference. It took mere days for "You forgot Poland!" to become an anti-Bush catchphrase, appearing on T-shirts and bumper stickers.

The Bushisms

Misspeaking will be the lasting legacy of Bush's public performances. But not all Bushisms are alike: they fall, fairly neatly, into three categories. In the first and classic version, it's easy enough to tell what the president was trying to say, even if he manages to mangle his syntax more spectacularly than you might have deemed possible.

("Families is where our nation finds home, where wings take dream"; "Suiciders are willing to take innocent life in order to send the projection that this is an impossible mission"; and his immortal commentary on the difficulties facing gynaecologists: "Too many OB-GYNs aren't able to practise their love with women all across this country.") In the second variety, the intended meaning is still discernible, but the result is almost zen-like, hinting at deeper significance or perhaps intentional humour. ("They misunderestimated me"; "What we Republicans should stand for is growth in the economy: we ought to make the pie higher.") Only a small number are truly, majestically baffling. "This is still a dangerous world," Bush noted in Iowa in 2000. "It's a world of madmen and uncertainty and potential mential losses." The incidence of good Bushisms has sharply decreased in recent years, though he was on good form last September in Washington DC, recounting a trip to the seaside. "I didn't grow up in the ocean," he said. "As a matter of fact - near the ocean - I grew up in the desert. Therefore, it was a pleasant contrast to see the ocean. And I particularly like it when I'm fishing."

The knack of being in the wrong place, at the wrong time

Nobody can really blame Bush for the fact that he was reading a book called The Pet Goat with a class of Florida schoolchildren on the morning of 9/11, though arguably he shouldn't have continued to do so after being informed of the attacks. (The unfair but amusing implication of much of the mockery seemed to be that books like The Pet Goat might have been the kind he naturally preferred - that he might have been reading The Pet Goat that morning even if he'd been scheduled to have the morning off, relaxing at home.) But it soon began to look like a pattern: when hurricane Katrina made landfall in New Orleans, Bush was on the tarmac of the airport in Phoenix, presenting John McCain with a large cake for his 69th birthday. (After posing for photographs, the two men abandoned the cake at the airport, where it melted in the heat.)

The record-breaking vacations

As with his verbal errors, supporters sought to portray Bush's many weeks at Prairie Chapel Ranch, near Crawford in Texas, as a virtue. The "western White House" was where Bush reconnected with real America, they explained - and what better way to experience the lifestyles of ordinary Americans than on a $1.3m, 1,583-acre ranch featuring four houses and a helicopter hangar? In 2005, with the Iraq war at its height, Bush headed to Crawford for five weeks - the longest presidential retreat for 36 years - spending his free time with chainsaw in hand, clearing mesquite, cocklebur and other uninvited plant life. It's never been conclusively established how much brush really needs clearing at Prairie Chapel; one local farmers' representative described Bush's brush-clearing as "highly recreational" but, to be fair, there's no evidence of aides having distributed brush especially so that the president could clear it.

The social inappropriateness

The competition is tough, but there's a strong case that the single most excruciating televised moment of Bush's presidency was the unsolicited back rub he bestowed upon the German chancellor, Angela Merkel, at the G8 summit in St Petersburg in 2006. The encounter barely lasts three seconds, in which the president approaches Merkel from behind and grasps her neck, prompting the chancellor to throw up her arms in shock, before hastily assuming an everything's-OK smile. But in those three seconds, Bush's fraternity-house jocularity makes a head-on collision with the world of diplomatic propriety, and it's painful to watch.

The shaky grasp of geography

"Often people ask me," Bush said last year, "'Why is it that you're so focused on helping the hungry and diseased in strange parts of the world?'" Many parts of the world did indeed remain strange to Bush, who sought to render them more familiar by bringing his own pillow everywhere he travelled. "Do you have blacks, too?" he is said to have asked the Brazilian president Fernando Cardoso in 2001, though the evidence for this anecdote is far from conclusive. As governor of Texas, he'd already caused a minor stir - in Slovakia and Slovenia, anyway - by confusing Slovakia and Slovenia, though by 2006 he was more focused on building "an Iran that is capable of resisting Iranian influence".