A specific, an easy, example would be the Huffington Post. Liberally minded people would naturally tend to read it for the political ideas there. However, the Huffington Post is actually a very large group blog and one of their bloggers is Joe Mercola. While Joe Mercola is technically a doctor, who holds very very very unscientific beliefs and blogs about them there, frequently linking to his site, mercola.com. So it seems reasonable that a person reading on Huffington Post might end up on Joe Mercola's site and believe what is there.
But I really don't think it starts or even stops with Huffington Post, and I certainly don't think it is only "the left" which is prone to these things. So I want to attempt to approach it vaguely scientifically using document and link analysis to create a graph where you can easily see how a person can go from Rational Site A to Irrational Site C.
It may turn out that the Huffington Post is actually just a special case and there is, in general, no easy way to explain how someone gains these beliefs purely from link and documents alone. For example, one of my friends mentioned the site "Zero Hedge" for his information. This site is very focused on finances, and barely seems to link out. And the bloggers are anonymous, so you really couldn't even just search for other stuff they have written. The only real thing I saw was an ad (which I saw on some other Libertarian sites) about how President Obama was working to destroy the 401(k) system. I could see this leading to other conspiracy type theories, but who knows.
In the process there will also be the generation of who are the "hubs" of the various non-scientific beliefs. Any how, will be cool to see how it works out.
I would be interested to know if this has already bee done or if anyone has any tips. Currently I am looking at some tools like Bixo and Bingo! to perform crawling and document classification.