Mitt Romney illustrated on an Etch A Sketch. (Ohio Art/Associated Press/Washington Post Illustration)

We do point out misstatements, though, and the public doesn’t often care. Only rarely is a politician made to pay full fare for even the most full-blown flight from reality. Instead, they’re punished for those moments when we’re made to hear the truth.

From Mitt Romney’s insistence that President Obama travels the planet apologizing to Newt Gingrich’s pledge to make gasoline sell for $2.50 a gallon, candidates often get applauded for rhetoric run amok.

My nominee for the most over-the-top tale of the primary so far is Rick Santorum’s dark fantasy about forced euthanasia in the Netherlands — where, in his telling, fearful grandparents accessorize with “do not euthanize me” bracelets and slink around hoping they never have to be hospitalized. The Dutch, never having heard of such, dispatched a TV reporter to ask the candidate what he was talking about. To which Santorum’s spokeswoman, Alice Stewart, did respond truthfully: “A lot of these things,’’ she said, “it’s a matter of what’s in his heart.”

(In my heart, I’m 24 and an heiress, as God intended; so what?)

Even false statements can be illuminating, of course, as when Santorum rationalized that Republicans who don’t vote for him must be less than serious about their religious faith.

But endlessly describing health-care reform as the end of life as we know it doesn’t make it true. And is it better or worse that Santorum at least seems to believe his mistaken but from-the-heart claims that under “Obamacare,” his daughter with Trisomy 18 would not have received the same care? While Romney, who says that we’re “only inches away from no longer being a free economy,” used to know better.

Either way, candidates would surely try harder to get it right if they weren’t rewarded for getting it wrong. Or regularly made to regret those occasions when the truth does trickle out.

When Jon Huntsman acknowledged some unastonishing facts about climate change, for instance, that was a permanent conversation stopper. Nancy Pelosi is still taking heat for saying in frustration what’s true of every piece of legislation — that we only find out every last implication of its passage after it becomes law.

Reporters interviewing Eric Fehrnstrom, senior campaign advisor to Republican presidential candidate, former Massachusetts Gov. Mitt Romney (Justin Sullivan/GETTY IMAGES)

Walter Mondale doomed his 1984 presidential chances by admitting that the winner of the race would have to raise taxes — which is exactly what the winner, Ronald Reagan, did. The current Republican front-runner’s father, George Romney, blew his shot at the presidency during his ‘68 run when he told an interviewer that after actually visiting Vietnam, he’d started to see that he’d been “brainwashed” by our military. (By today’s lights, the follow-up would have been, “And?”)

Sometimes a little taste of hard truth doesn’t matter too much — as when Mitt Romney remarked in a debate that he was plenty worried about employing undocumented workers — because, as he’d told the guy who’d then hired other guys to mow his lawn, “I’m running for office, for Pete’s sake.

Or when, at a Romney campaign event in Maryland on Wednesday, a businessman in the crowd told him, “I haven’t failed yet,’’ and the candidate replied that it was still early. “You will’’ fail, Romney cheerfully assured the man, adding that “it’s in the nature of the private sector.” (Again, true — but also something that, if uttered by Obama, would have been seen as proof positive of his contempt for capitalism.)

Romney advisor Eric Fehrnstrom’s Etch a Sketch remark, however, does not fall into the category of a truth the public doesn’t like but will soon forget about. All he said was that the general election is so different from a primary that it’s “almost like an Etch a Sketch. You can kind of shake it up, and we start all over again.’’ Which is an unforgettable metaphor for a candidate with a history of some pretty severe flexibility on the issues.

Of course campaigns do start all over again in the general. (As Jordan Baker reminds her betwixt-and-between friend Daisy Buchanan in “The Great Gatsby,” “Life starts all over again when it gets crisp in the fall.”)

But since one of the biggest Republican knocks on Obama is that we still don’t know who he is, a challenger who can see him and raise him on the vagueness front is an unlikely antidote.

With seven months to go until Election Day, there will be lots of opportunities for Romney to recover. Only the feeling of inevitability that follows his win in Illinois this week is not at all the one he had in mind.

Melinda Henneberger is a Post political reporter and anchors “She the People.” Follow her on Twitter at @MelindaDC.