Yesterday, The New York Times published an op-ed by Columbia tax law professor Michael J. Graetz, exploring, as the headline had it, “Mitt Romney’s financial mysteries.” In short, why hasn’t Mitt Romney released more than one year (perhaps soon two) of his tax returns? What could be in them that Romney might not want registered voters to see?

These are legitimate questions that have vexed the campaign press and, presumably, some share of the voting public for months. And Romney’s weird reactions to this line of questioning—“That’s all that’s necessary for people to understand something about my finances,” and not wanting to give the Obama camp “more pages to pick through, distort and lie about”—haven’t exactly dampened the inquiries. Further digging by campaign reporters is entirely warranted.

Graetz—who was deputy assistant Treasury secretary for tax policy from 1990 to 1991, and an assistant to the Treasury secretary in 1992 under President George H. W. Bush—offered some informed speculation on these questions to Times readers, writing expertly of the IRS and IRAs. “Until Mr. Romney recognizes the right of voters to understand the finances of their leaders,” wrote Graetz, “all we are left with is speculation.”

That doesn’t mean you publish anything anyone says.

Which is what The Huffington Post’s Sam Stein and Ryan Grim did yesterday in a piece headlined, “Harry Reid: Bain Investor Told Me That Mitt Romney ‘Didn’t Pay Any Taxes For 10 Years’”, and for which we stick them with this week’s Dart.

After being granted a “wide-ranging interview” with Senate Majority Leader Harry Reid “from his office on Capitol Hill,” Stein and Grim proceeded to give Reid everything he could have wanted from that sit-down—including wide transmission of the following:

Saying he had ‘no problem with somebody being really, really wealthy,’ Reid sat up in his chair a bit before stirring the pot further. A month or so ago, he said, a person who had invested with Bain Capital called his office.

“Harry, he didn’t pay any taxes for 10 years,” Reid recounted the person as saying.

“He didn’t pay taxes for 10 years! Now, do I know that that’s true? Well, I’m not certain,” said Reid.

In short, as New York’s Dan Amira summarized the piece, “Harry Reid heard from some guy that Mitt Romney didn’t pay taxes for ten years…Awesome scoop, Harry Reid.”

Make that: Awesome scoop, HuffPo.

Some more from that scoop:

Tellingly, neither Reid nor his office would reveal who the investor was, making it impossible to verify if the accusation is true. And as his quote makes clear, he’s uncertain if the information is accurate. The Romney campaign’s press secretary, Andrea Saul, has previously denied rumors that Romney didn’t pay “any taxes at all.”

But there is limited political downside to the type of open speculation that Reid is making, so long as Romney refuses to budge on the issue of his tax returns…

Especially so long as there are reporters willing to write up that “open speculation” and ensure its dissemination to a wider audience, and to present the story in a way that drives attention to Romney’s evasiveness rather than to Reid’s gleeful disregard for what the truth actually may be. The HuffPo reporters did, to their credit, note clearly that Reid’s claims are unsubstantiated—but that just highlighted how flimsy the claims are, and how reckless their dissemination is.

What would have been a less Dart-worthy approach? Reid’s comments could have been ignored (as a similarly unsubstantiated claim on the Senate floor, excavated today by Stein, seems to have been). Or the story could have foregrounded not the (entirely newsworthy!) controversy over Romney’s taxes but the untrustworthiness of Reid’s account—that, after all, is the part of the story that was unique to HuffPo.

Instead, the article comes across as an instance of mutual exploitation—Reid keeps questions about Romney’s taxes in the headlines (and not just on HuffPo), while HuffPo gets a splashy “exclusive” that draws a ton of Twitter buzz. And in the process, they create incentives for more politicians to act just as Reid did here.

In his follow-up piece today that flagged Reid’s earlier comments, Stein offered this account:

Either way, the political implications of Romney’s tax history eclipse the question of the identity of Reid’s anonymous Bain source. Romney’s refusal to release further tax return data has left the door open for his critics to dispense with the presumption of innocence and speculate openly about what possibly nefarious details he is trying to hide.

But the press has agency here, too, and needs to draw some important distinctions: informed speculation like Graetz’s can enlighten readers and show paths to aggressive, responsible reporting. Open speculation, like Reid’s, does neither.

If you'd like to help CJR and win a chance at one of 10 free print subscriptions, take a brief survey for us here.

Liz Cox Barrett and Greg Marx are CJR staff writers and co-editors of The Swing States Project.