it doesn't necessarily have to be true.
he can present slanted information, that leads you to believe something that is false, but never come right out and say it.
he can come right out and say a damaging lie. but if you can't prove it's a lie, he's OK. (since the burden of proof is on the accuser, if you are accusing him of lying, you have to prove it's a lie, he doesn't have to prove it's true)
he can also ask questions and only keep the parts of your answers that prove his point, while editing out things he doesn't.
for example- Q: is it true that you never donate money to the salvation army guys at Christmas time?
A: Yes. however I do donate 50% of my income to various charities.
it's perfectly legal to play the interview with everything from 'however' forward edited off. so with a little creative editing you can make a very generous guy look like a selfish penny pinching miser.
thats the real problem with Moore. in order to do a more sensational or hyped film, he will blow right past reasonable limits, so you have to take what he says with a grain of salt.
you watch a movie of his and take note of his claims, but they aren't proof and you don't quote him, you check them out for yourself first.
it's not like there is any lack of real, honest proof of questionable activities in this administration. if he'd stick to that he could present a much more honest and significant point. he probably would sell as many tickets though, and thats the real bottom line.
he's hard to take seriously because you just can't trust anything he says without checking it out first. most of it checks out, but but if he can't find enough evidence to prove what he wants to prove, he's not above creating some with editing.
if you are gullible enough to believe everything he says and go quoting it without verifying first, be prepared to look stupid.