A documentary is not, by definition, objective.  It merely 'documents' something, all through the filter of the person making it.

New Journalism came about with Tom Wolfe and Joan Didion, then got launched into some kind of stratosphere with Hunter S. Thompson. There's a great quote in Fear and Loathing on the Campaign Trail about objectivity in journalism, suggesting, as any student of literature would guess, that it simply cannot exist.

Anyway, there's a stub in Wikipedia, too.

Moore's slipshod relation to the facts gives him a credibility problem. People who frequent dKos already understand that there's an equal/greater credibility problem with the SCLM, but if someone does not see that, then when the SCLM talks about Moore's credibility problem, you end up with half the story and hate the wrong person.

I think Franken takes this up in Lies: he suggests that his book was thoroughly fact-checked--in comparison to, say, Coulter's work. Part of this was, from my understanding, because Franken understood that, when held to a higher standard like the left is, he has to hit everything square. Coulter can suffer the accusations of bad facts--the SCLM will let her slide. But Franken knows that he has no similar friends in there. Hence, he has to make sure it's all dead on.

This all said, Fahrenheit 9/11 was pleasant largely because Moore managed to present everything so straight--though I still could have handled less snark (starting the flick with a dud of a joke about who makes up Moore's dreamscape, for example, annoyed me). Maybe I just don't like jokes.