I suspect two hours of debate moderation isn’t easy, so I’m inclined to cut CNN’s Anderson Cooper some slack for last night’s less than stellar moments. At one point, for example, he asked Herman Cain, “Are either Governor Perry or Governor Romney, are they the ones who should be president?” That’s not a good question.

But some errors are more problematic than others. Zachary Pleat flagged an important misstep in this question to Michele Bachmann:

“[Y]ou said in the last debate that everyone should pay something. Does that mean that you would raise taxes on the 47 percent of Americans who currently don’t pay taxes?”

The question is based on a false assumption. It’s popular in Republican circles and on Fox News — and Cooper may have slipped up because he’s heard the bogus line so many times — but the truth matters here.

The notion that 47 percent of Americans currently don’t pay taxes is just wrong. In case anyone’s forgotten, millions of Americans may be exempt from federal income taxes, but they still pay sales taxes, state taxes, local taxes, Social Security taxes, Medicare/Medicaid taxes, and in many instances, property taxes. It’s not as if these folks are getting away with something — the existing tax structure leaves them out of the income tax system because they don’t make enough money to qualify. Some are students, some are unemployed, and many are retirees who can’t earn an income because they’re no longer in the workforce.

I’m hoping Cooper just misspoke, meant to add the word “income” to his question, and didn’t actually intend to endorse the bogus Republican talking point. Either way, it warrants a correction.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.