A man standing on a street corner with a sign reading "the lizard people rule you all," or, "my neighbors are spying on me for the government" isn't likely to get many supporters.
But give that man a Web site template, or let him produce some slick videos on YouTube and, lo and behold, he may have thousands of people across the world supporting him.
Such is the story of several extraordinarily popular conspiracy theorists and theories online today.
Take the victims of gang stalking -- a subculture of people who think their friends and neighbors are all secret government spies ready to turn them over to the authorities. The movement has recently spawned gang stalking support groups, forums and advice Web sites.
Or take the former journalist and BBC sports announcer, David Icke, for example.
Icke was laughed out of the public eye in the early '90s when he started wearing only turquoise and explaining that voices had sent him on an important mission to save the earth.
Decades later, Icke has written books, has fans in 47 countries and can gather a crowd of 2,500 people in a city simply by posting a date for a lecture on his Web site.
The cornerstone of Icke's theories is that a malicious race of lizard people -- the "shadowy elite" -- rules the world and all its political leaders primarily by controlling the media and orchestrating fear-mongering catastrophes, such as Sept. 11. Icke said he already has speeches lined up for 2009 in Los Angeles, Mexico, Croatia, New Zealand and Australia.
"I knew about the mainstream media, and that the mainstream media has a stunning level of myopia so that only that which is in the mainstream will be presented," said Icke. "What the Internet has done [is that it] has allowed information to flow outside of the myopia. ... The Internet has been absolutely essential."
The Internet has always been a forum for fringe ideas, but success like Icke's, and subcultures built on paranoid theories like gang stalkers, points to an understudied corner in psychiatry: Who are the people who believe such theories in the quiet of their homes, and what does such behavior mean for a person teetering on the edge of mental illness?
"It's not an area that has been studied very well," said Angus MacDonald, a spokesperson for the mental health charity NARSAD, and an associate professor of psychology at the University of Minnesota in Minneapolis.
MacDonald cautioned that not everyone who believes in a conspiracy plot is mentally ill. They just may be suggestible or just suspicious of authority.
For the healthy in mind, MacDonald said, "it's a wild card about whether this is going to improve people's state or not. It may turn out that the value of the community is greater than the destructive nature of the narratives that are spun out of them.
"But on the same point, this is a domain that didn't need more wild cards," he added.
Whether or not conspiracy theories harm people who are susceptible to mental illness is a matter of debate among psychiatrists.
"Most people with major mental illness don't believe in conspiracy theories," said Dr. Ken Duckworth, medical director of the National Alliance of Mental Illness.
Duckworth likes to imagine a Venn diagram with one circle representing people with paranoid psychosis and another circle representing people who believe conspiracy theories.