This Young Turks clip shows exactly how NOT to do fact-checking.
This one involves Obama's assertion in the debate that Romney is offering a $5 trillion tax-cut and that, in so doing, will be forced to either blow up the debt or cut middle-class tax breaks like the deductions for mortgages and charitable donations.
So here's how CNN fact-checks this argument. After conceding that Mitt Romney has indeed proposed a 20% tax-cut across the board, CNN then says:
Romney says he will offset that by closing loopholes and reducing reductions.
So if we take him at his word, the verdict that Mitt Romney will cut taxes on the wealthy by $5 trillion dollars is false.
So that's what fact-checking has become? Just taking someone's word for it?
Here it is at the 4:15 mark, but I would advise watching the whole segment just to see how Cenk and Ben Mankiewicz skewer the network for this obvious fact-checking fail.