Gore has so many odd tics and phony gestures that it's hard to pin down which trope it is that makes him seem so bizarre. He has progressed from speaking to us as if we're retarded, to speaking to us as if we're retarded and deaf. The same way gay men exaggerate feminine gestures, Al Gore exaggerates human gestures, wildly overarticulating his every syllable.
It's true you can't imagine Al Gore ever making a slip of the tongue, as George Bush sometimes does. But only for the same reason that you can't imagine the computer recording on a business answering machine making a slip of the tongue -- the difference being that a computer voice doesn't have the capacity to condescend to you like Al Gore does. Bush occasionally makes a slip of tongue because he's human.
In addition to the thunderous sighs, Gore constantly interrupted Bush to make "just one more point." Nut-mail always has this quality, with the "one more point" typically being written around the margin of the paper. Even the unflappable, phlegmatic Jim Lehrer started rolling his eyes at Gore's incessant interruptions.
Another oddity is that Gore is forever smiling at inappropriate moments. In a tedious monologue on campaign financing, he went from a deep, angry frown to a maniacal grin in the course of this single sentence -- "our system of government (frown, frown, frown) is being undermined by too much influence coming from (huge beaming smile!) special interests money." Neither the frown nor smile was consonant with his words. He's really strange.
I suppose it's possible for a peculiar freak of nature to make a good president, but Al Gore wouldn't. Though he did make it through the first debate without claiming to have invented anything or to have been the inspiration for any major motion pictures, Gore repeatedly wheeled out his promise to put Social Security in "an iron-clad lock box" where the politicians can't touch it. If Gore can invent a lock box politicians can't pick, he won't be stuck bragging about inventing that measly Internet anymore.