(Robyn Beck/AFP)

The first debate between Donald Trump and Hillary Clinton is a mere 27 days away, and the candidates have begun their preparations. In ordinary circumstances, watching and interpreting the debates can be an exercise in cutting through the pre-planned zingers and shutting your ears to the river of drivel emanating from the spin room in order to find something genuinely enlightening in the whole spectacle.

But from what we’re hearing, this year could really be different. This time, the debates could truly reveal both candidates in full.

Debates are, at best, an imperfect forum for judging candidates. On the positive side, they give us the longest sustained view most of us will ever have of the two, a stark contrast to the 30-second ads and eight-second soundbites on the news that make up most of what we see of the contenders. We get to see them probed at length about issues, see how they react to a stressful situation, and hopefully get some window into their thinking.

Trump, along with Paul Manafort, Reince Priebus, and Jeff Sessions, faced questions Sunday about possible changes to the debate schedule which was set by an independent commission in 2015. (The Washington Post)

On the other hand, debates are performances, and ones that the president will not have to repeat until he or she runs for reelection. You can be a skillful debater and a terrible president, and vice-versa; it’s not as though Barack Obama has to stand on a stage trading barbs with Mitch McConnell or Xi Jinping to determine what American policy is going to be and whether it will accomplish its goals. The news media, furthermore, tend to focus their post-debate coverage on gaffes and gotchas, repeating those allegedly decisive moments over and over until all of us have forgotten everything else that we actually saw. And you’ll notice that the supposedly critical gaffes are nearly always the ones that reinforce the conclusions reporters have already made about who the candidates are.

But for all those weaknesses, debates can still deepen our understanding of these two people. And that may be more true than ever this time. Let’s take a look at this report in today’s New York Times, with some behind-the-scenes information about the contrasting ways Clinton and Trump are preparing:

[Clinton’s advisers] are undertaking a forensic-style analysis of Mr. Trump’s performances in the Republican primary debates, cataloging strengths and weaknesses as well as trigger points that caused him to lash out in less-than-presidential ways.

As Mrs. Clinton pores over this voluminous research with her debate team, most recently for several hours on Friday, and her aides continue searching for someone who can rattle her as a Trump stand-in during mock debates, Mr. Trump is taking the opposite tack. Though he spent hours with his debate team the last two Sundays, the sessions were more freewheeling than focused, and he can barely conceal his disdain for laborious and theatrical practice sessions….

He has been especially resistant to his advisers’ suggestions that he take part in mock debates with a Clinton stand-in. At their first session devoted to the debate, on Aug. 21 at Mr. Trump’s club in Bedminster, N.J., the conservative radio host Laura Ingraham was on hand to offer counsel and, if Mr. Trump was game, to play Mrs. Clinton, said Trump advisers who spoke on the condition of anonymity because the debate preparations were supposed to be kept private. He declined.

Instead, Mr. Trump asked a battery of questions about debate topics, Mrs. Clinton’s skills and possible moderators, but people close to him said relatively little had been accomplished.

This picture is assembled from the anonymous comments of aides and other people involved in the campaigns, so at least some of it was passed to the reporters in an attempt to shape expectations of the debates, rattle their opponents, or for some other reason. But that doesn’t mean it isn’t true. We see Hillary Clinton as methodical and thorough, approaching the debates like any test demanding lengthy preparation. She may not be the most natural performer, but she’s going to do her homework and try to prepare for every eventuality. She’s immersing herself in briefing books and the meticulous research she has instructed her people to carry out.

Trump, on the other hand, is impatient, intuitive, and impulsive, easily distracted and bored with details. He doesn’t care about policy. Instead, he’s shooting the breeze with a bunch of media people, including Roger Ailes and Laura Ingraham. If Clinton believes that substance is essential to winning a battle of optics, Trump thinks that optics are the only thing that’s important. That has been the defining characteristic of his career: succeed through creating an impression of success until the image becomes reality (or at least until you’ve sold enough seminars to take your money and skedaddle).

So even if there’s going to be plenty of spin and plenty of attempts to give misleading impressions to viewers, in the end these debates will probably show us the truest expressions we could get of who these two candidates are. They may come up with a few planned answers that subvert expectations — Trump showing a surprisingly nuanced grasp of some issue, or Clinton resisting the urge to give an extended exploration of policy detail — but as the hours go on, we’ll see both of them for who they really are.

If that happens, the debates won’t produce a major swing in the polls, as we in the media often seem to hope they will (for the sake of drama if nothing else). But they’ll still be a critical step on our way to November, and to the next presidency.