In a nutshell the reason you should use fact checking websites (such as snopes, politifact, factcheck and wikipedia) is that there is a lot of misinformation circulating around, especially in e-mails that commonly circulate around. In general the reason why you should trust the fact checking websites is that they have established an impressive track record of accuracy. Were they not right nearly all the time that fact would have been pointed out and would be posted all over the Internet. They are completely independent of each other- operated by different organizations, but their consistency with each other is extremely high. Lastly you should trust them because they are respected, trusted and quoted by other credible organizations, such as CNN, FOX and MSNBC. Among other well-respected, non-partisan, non-political organizations that have done some fact checking of their own that is consistent with the fact checking websites listed above are: AARP (see: http://bit.ly/gDE30) and PBS (see: http://bit.ly/7uAOf). The following are some details on each of the main fact checking websites:
Snopes.com, also known as the Urban Legends website, is a web site that is the best-known resource for validating and debunking urban legends, Internet rumors, e-mail forwards, and other such stories of uncertain or questionable origin in American popular culture. Snopes is run by Barbara and David Mikkelson, a California couple, who founded Snopes.com in 1995.
Snopes has established their credibility with me simply because I have probably checked it more than a hundred times and have never found anything they said not to be true. Nor have I read or heard anywhere where anyone has ever found anything they have said to be untrue. That is an incredible record of accuracy. Occasionally I have checked it with other fact checking websites, such as Wikipedia, Politifact and factcheck.org. Never have I found an inconsistency. Also, Snopes provides their sources at the bottom of their articles, so that you can see where they got their information from. This makes it easy for the user to verify their information. The site is well established—it has been operating since 1995. The site is often referenced by the news media and other credible sites, including CNN, FOX news (the king of the right wing media), and MSNBC. Thus their credibility is well established with other credible organizations.
Regarding the allegation of any liberal bias- which its critics often cite, you can check the following web pages to verify that Snopes has reported errors in circulating e-mails related to the Republican candidates, just like they have for the Democratic candidates:
http://www.snopes.com/politics/mccain/mccain.asp
(6 of 12 circulating McCain e-mails reported as false)
http://www.snopes.com/politics/palin/palin.asp
(8 of 10 circulating Palin e-mails reported as false).
FactCheck reviewed a sample of Snopes’ responses to political rumors regarding George W. Bush, Sarah Palin and Barack Obama, and found them to be free from bias in all cases. FactCheck noted that Barbara Mikkelson was a Canadian citizen and David Mikkelson was an independent who was once a registered Republican. You’d be hard-pressed to find two more apolitical people.
PolitiFact is a project of the St. Petersburg Times to help you find the truth in politics. Every day, reporters and researchers from the Times examine statements by members of Congress, the president, cabinet secretaries, lobbyists, people who testify before Congress and anyone else who speaks up in Washington. They research their statements and then rate the accuracy on their Truth-O-Meter – True, Mostly True, Half True, Barely True and False. The most ridiculous falsehoods get our lowest rating, Pants on Fire.
FactCheck.org is a non-partisan, nonprofit, website that describes itself as a “‘consumer advocate’ for voters that aims to reduce the level of deception and confusion in U.S. politics. It is a project of the Annenberg Public Policy Center of the Annenberg School for Communication at the University of Pennsylvania, and is funded primarily by the Annenberg Foundation. Most of its content consists of rebuttals to what it considers inaccurate, misleading, or false claims by politicians. FactCheck has also targeted misleading claims from various partisan groups.
Wikipedia is a multilingual, Web-based, free-content encyclopedia project. Wikipedia is written collaboratively by volunteers from all around the world. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference web sites containing more than 13 million articles. While anyone with access to the Internet can contribute to Wilipedia, the effectiveness of its internal policing has to be incredibly good, because I have checked it over 100 times and have never found anything inaccurate in it.
Posted by Roger Kuder 
Roger Kuder's Blog 