Whenever I debate twoofers, I notice that they seem to work under a fair number of implicit rules. A lot of them are like standard woo, but it seems to stick out a lot more when I read them.
1. Ad hominem is the basis of all reality: Broadest form of pretty much all these other rules: Who you are makes your argument valid, not the internal logic or physical evidence.
2. Evil = Power: Because Bush is evil enough to do something, there's no need to prove that the laws of physics would allow him to do that something. No need to worry about the administrative nightmare of managing thousands of rogue ninja demolition crews, either.
3. Anonnies and people with pseudonyms are automatically wrong because they might possibly have something vaguely resembling a government connection. Therefore, if a conspiracy skeptic posting under a blog name, rather than his real name, says the sky is blue, then obviously it must not be. Exception: Twoofers who use fake names, after all, they're the only people who have something honest to protect, and they're the only people on the entire surface of the Earth who don't want death threats sent to their snail mail address or government suppression squads at their front door or office.
4. Using your real name = Infinity Plus One times your normal credibility. Being ridiculed by snail mail or physical presence when someone figures out where you live boosts your credibility level far more than email or forum ridicule because Galileo didn't have an email address.
5. People who are standing up against The Man are automatically right. Outspoken liberal skeptics who berate government officials for trampling on science, trying to get Intelligent Design in schools, employing various ineffective or even counterproductive "War on [Concept]" measures, destroy civil rights, engage in historical revisionism, or whatever aren't doing enough: They have to sit on their rears talking/posting about being certain of the government using Orbital R-9 Wave Cannons in order to count as being opposed to the administration. Anything less, and they're exactly as loyal as any Bush crony, and thus automatically wrong.
6. If it doesn't sound like a TV/movie plot, it's not realistic. There's ALWAYS a frame-up, an "unexpected" plot twist, or whatever. If the evidence is rock solid, that just means the guy doing the framing/set up/whatever is more elaborate about the level of evidence he plants.
Feel free to extend the list in the comments.