Except for providing political journalists with millable grist, what good are endorsements? Obviously, a presidential candidate can’t win his party’s nomination on the power of endorsements alone. If that were the case, as Vanity Fair‘s Todd S. Purdum pointed out last month, Al Gore’s anointment of Howard Dean in 2004 would have worked magic.

Yet candidates continue to whore for endorsements, and other politicians continue to give them for mysterious reasons. Take, for example, John McCain’s endorsement of Mitt Romney yesterday at a New Hampshire campaign stop. McCain doesn’t bother to mask his low regard for Romney, as the New York Times reports today in a piece about the event:

[T]he two men made little eye contact, even when Mr. Romney was introducing Mr. McCain. They shared a stiff, half-hug on stage, patting each other on the back in a perfunctory manner.

Placing the relationship in historical context, the Times explains that in 2008, when both men were running for president, McCain hissed that Romney would say anything to get elected. In a 2008 debate, Romney accused McCain of “dirty tricks” and McCain said Romney didn’t have “the experience and the judgment” to be commander-in-chief.

If endorsements were about reciprocity, McCain would have supported Jon Huntsman this year as Huntsman spurned fellow Mormon Romney in 2008 to support McCain. But endorsements aren’t a matter of deposit and withdrawal. They signal information—some of it quite useless—to the political universe about both the endorser and the endorsee.