Yesterday we saw the AP check President Clinton's facts by pointing out an instance in which he failed to tell the truth.  This occasioned a chorus of boos from the world.  Undaunted, the AP clarified its position.  Before we get to that, here is the original passage.

CLINTON: "Their campaign pollster said, 'We're not going to let our campaign be dictated by fact checkers.' Now that is true. I couldn't have said it better myself — I just hope you remember that every time you see the ad."

THE FACTS: Clinton, who famously finger-wagged a denial on national television about his sexual relationship with intern Monica Lewinsky and was subsequently impeached in the House on a perjury charge, has had his own uncomfortable moments over telling the truth. "I did not have sexual relations with that woman, Miss Lewinsky," Clinton told television viewers. Later, after he was forced to testify to a grand jury, Clinton said his statements were "legally accurate" but also allowed that he "misled people, including even my wife."

The job of a fact checker seems simple enough in this case.  You merely need to see whether Clinton has accurately represented the words of the Romney campaign's Pollster.  The answer is yes, by the way.  Whether Clinton lied in the past is completely irrelevant.

Perplexed at all of the hoopla over this manifestly ridiculous passage, the AP defended themselves as follows.

The reference was not about that woman, Miss Lewinsky. It was about facts. Clinton challenged the Republicans for their attitude toward facts. We were simply pointing out that as president Clinton had his own challenges in this area.

Yes, we got that.  But it's still irrelevant to whether what Clinton said was true. 

In case anyone is still confused, this is the way ad hominems work.  When a person's character tends to make that person's judgments suspect, then it is legitimate to point that out.  When such facts about a person are irrelevant to whether the claims they make are true, pointing out those facts are irrelevant and so fallacious.  People may have a tendency to disbelieve Clinton, the fact checker's one single job in this case is to tell us whether he was lying.  He wasn't.

Besides, how does Clinton's having lied in the past excuse the Romney campaign from lying now?