I've found that many of those who believe wild conspiracy theories (and who tend to become offended and scoff at skeptics with a wave of the hand and a dismissive, 'do you believe everything the government tells you?'), believe it on the local level as well. Once again, it amazes me how much faith people tend to put in conspiracies that involve real, live, breathing human beings.
An effictive conspiracy, I believe, would directly involve as few people as possible. The more who know, the more chances that the secret can be revealed. The simpler the conspiracy, the easier to hide.
The entire idea that the government would have concocted a complicated, muddled plot like 9-11 is bizarre. IF there were such a conspiracy by the governemnt, and they wanted to create a terrorist attack and bring down the towers, why on earth bring into the picture passenger jets that would by necessity involve so many more in on the plot.....
The Human Factor will get you every time.