Agreeing on the facts when you disagree about how to react to them has become rare, and some tools people rely on instead of personal investigation are less reliable than they'd like to think.
Joel Rosenberg links to an example. The question is whether the Democratic Party's presidential candidate, Barack Obama, claimed he would serve his full senatorial term and would therefore not run for president in 2008. Mr. Obama is quoted in an interview with Tim Russert as saying:
Russert: When we talked back in November of ‘04 after your election, I said, “There’s been enormous speculation about your political future. Will you serve your six-year term as United States senator from Illinois?” Obama: “Absolutely.”
Obama: I will serve out my full six-year term. You know, Tim, if you get asked enough, sooner or later you get weary and you start looking for new ways of saying things. But my thinking has not changed.
Russert: So you will not run for president or vice president in 2008?
Obama: I will not.
Apparently there's a discrepancy between this quote and how the story is reported at Snopes, and those of us who are accustomed to relying on Snopes should be wary. Now, maybe this is the only discrepancy on the entire site, but that seems unlikely.
You'll note I did not title this "Obama lies" or similar; that's intentional. I believe most elected officials have said things and then later changed their minds, and I don't consider that a lie necessarily. But Snopes is clearly wrong to claim he never said it.