What’s going on? Romney seems to have what New York Times Washington bureau chief David Leonhardt called a pattern of “bad days after good wins.” Politico’s Dylan Byers notes that “Every time it seems like Mitt Romney is stepping into his groove, he goes and says something that kills his momentum.” And TPM’s McMorris-Santoro went so far as to try to create “an exhaustive list” of the times that Romney has “squashed good news like a bug at a Mississippi campaign rally.”

The most obvious explanation is that Romney is not a gifted politician and sometimes inadvertently reinforces stereotypes of himself as rich, awkward, a flip-flopper, etc.—or comes close enough that the media can frame the episodes as consistent with the narrative—but that does not entirely explain the Fehrnstrom explosion. While the Etch-a-Sketch line might have attracted some attention in any context, it is likely that the media is especially receptive to potentially damaging anecdotes about Romney after wins because he is very likely to win the nomination. The hype around these gaffes helps to meet the professional and economic incentives to maintain viewer and reader interest in the race despite the overwhelming odds faced by Romney’s rivals.

In an attempt to justify the media feeding frenzy, some of the coverage offered explicit arguments about the significance of the episode—but that meta-commentary only illustrated how the media tends to exaggerate the importance of episodes like this one. For example, The Washington Post’s Chris Cillizza claimed that “what this episode highlights is how small things in modern politics can — and often do — become big things”:

Swiss cheese on a cheesesteak. Uncertainty about how many houses you own. Corporations are people too. Windsurfing as a pastime. Curt Schilling as a Yankees fan. And those are just the handful we thought of off the top of our heads.

…Small things are also often seen by voters as a window into the true nature of a candidate or a campaign. It wasn’t that John Kerry ordered swiss cheese on his cheesesteak; it was that in so doing he proved he wasn’t a regular guy. It wasn’t that George H.W. Bush seemed to be amazed at a grocery scanner; it was that it affirmed that he was out of touch with the pocketbook concerns of regular people.

Which brings us back to the Etch-a-Sketch incident. What Fehrnstrom actually meant doesn’t matter at this point. The Etch a Sketch line will now have a life of its own that will continue to be a sore spot for Romney and his campaign for the foreseeable future. (Can you really see a scenario where Democrats drop it entirely? We can’t.)

One sentence about an Etch a Sketch isn’t going to decide whether Romney will be the Republican presidential nominee (he almost certainly will) or whether he can beat President Obama in the fall.

But, it’s one more piece of evidence that Democrats will use to paint Romney as a politician’s politician — willing to say whatever he thinks the audience he’s in front of wants to hear.

And that’s why it matters.

But even if the episode is just “one piece of evidence,” we should be able to find some indication that campaign gaffes affect voters. In reality, though, the evidence suggests that these types of events have little electoral significance. None of the gaffes that Cillizza highlights—from Swiss cheese on a cheesesteak to uncertainty about how many houses you own—had significant effects on the outcome of those presidential campaigns. (In addition, the grocery store scanner episode is disputed and appears to be false.)

Brendan Nyhan is an assistant professor of government at Dartmouth College. He blogs at brendan-nyhan.com and tweets @BrendanNyhan.