During and before the four years Hillary Clinton was secretary of state, the Clinton Foundation run by her husband took tens of millions of dollars from foreign governments and corporations.

Many of these donors had a lot riding on Clinton’s decisions. Saudi Arabia gave the foundation up to $25 million, and Clinton signed off on a controversial $29 billion sale of fighter jets to the country. Oil companies gave the foundation around $3 million, and Clinton approved a lucrative gas pipeline in the Canadian tar sands they’d long sought.

We've known the basics of this story for months now. But another media feeding frenzy over the foundation kicked off again on Monday, when the State Department was forced to release emails showing that the foundation’s leadership tried to land its top donors meetings with the secretary of state.

Clinton’s defenders say the new disclosures don't amount to much. Certainly, none of them offers proof that Clinton was willing to trade government favors directly for big contributions. Moreover, as Mother Jones’s Kevin Drum writes, most of the donors’ requests to see Clinton were actually turned down.

Many of the donors she did meet with — people like the crown prince of Bahrain and Nobel Peace Prize Winner Muhammad Yunus — were more or less exactly the kind of people you would think would be able to get a meeting with a Cabinet secretary.

So if there was no quid pro quo, does that mean Clinton's conduct was aboveboard? I interviewed four experts this week — and their answer was that the Clinton really did risk dramatically escalating an already serious problem with money’s influence in politics.

Why money in politics experts are upset over the Clinton Foundation’s ties to the State Department

The key to understanding why good government advocates are upset about the new revelations is to first get past the argument that Clinton Foundation donors were transactionally rewarded for their gifts.

This is not what my sources argued. Instead, the heart of their complaint was that the foundation’s contributors appear to have gained a greater ability to make their voices heard by Clinton’s State Department by virtue of donating to her husband’s private foundation.

This is why they see the new email disclosures as such a big deal. Talking with top government officials obviously isn’t the same as getting them to do your bidding, but doing so can help structure how they think, whom they turn to for advice, and, ultimately, what they decide to do. And the emails at least strongly suggest that foundation donors had a better opportunity to mold the secretary of state’s worldview than they would have otherwise.

Here’s what Bob Biersack, a senior fellow at the Center for Responsive Politics, told me:

Having the State Department opening its doors to foundation donors suggests that the people who are giving to this foundation will get consideration from the Clintons in the context of their work — in her case, the US diplomatic process and possibly more. This risks creating an environment through which you think through problems, make decisions, and seek information when you’re trying to analyze complex situations. It takes a big effort to get beyond that. Clinton might think, "These people are interesting, and they’re doing great work, and they’re helpful to me and my husband." That’s just human nature. But the basic, core problem here is that you’re creating a geography for your thinking that’s definitionally narrow — and based partly on who has money. They had the opportunity to present their case to the State Department in ways other people don’t.

Why it sure looks like foundation donors got easier access to the State Department

How do we know foundation donors really did get better access to Clinton’s State Department? Well, it’s impossible to prove — no Clinton staffer was stupid enough to write, "Thanks for giving $10 million to Bill! Now we can get coffee!"

But the circumstantial evidence is pretty strong. Here are some of the highlights:

Douglas Band, the Clinton Foundation’s top executive, asked the state department if Clinton could meet with "our good friend" Bahraini Crown Prince Sheikh Salman. Salman, who had given the foundation $32 million, met with Clinton. Clinton later approved a $630 million arms sale to Bahrain, according to the International Business Times.

A Ukrainian magnate named Victor Pinchuk gave the Clinton Foundation between $10 million and $25 million. While Clinton was secretary of state, her aides set up "about a dozen meetings with State Department officials on behalf of or with Mr. Pinchuk to discuss the continuing political crisis in continuing political crisis in Ukraine," according to the New York Times.

In 2009, Band told Clinton aide Huma Abedin to secure a meeting for a Lebanese billionaire who had also given millions to the foundation. That donor, Ronald Chagoury, controlled a development in Lagos where the State Department was considering constructing a consulate, according to CNN. (The consulate wasn’t built.)

S. Daniel Abraham, a billionaire who gave up to $10 million to the Clinton Foundation, was also granted access to meet with Clinton, according to the released emails. (Abraham is also the head of the Center for Middle East Peace.)

A top Clinton Foundation executive left about 150 voicemails for state department aide Cheryl Mills over the course of two years, according to call logs obtained by Fox News.

While secretary of state, Clinton met with at least 85 donors who had given the foundation as much as $156 million, according to the Associated Press. And that’s just the ones we know about. (As the AP has pointed out, the State Department is stonewalling the release of Clinton’s schedule — meaning we probably only know a fraction of the actual meetings she held with donors.)

Again, you don’t have to think Clinton is corrupt to think she was probably more likely to meet with people in her family’s orbit. And you don’t have to be a conspiracy theorist to think it’d be easier to be in her orbit by giving buckets of cash to her family’s charity.

"There’s no doubt in anyone’s mind that a large number of the Clinton Foundation donors who met with her gave partly to get access to the Clintons," says William English, a professor of ethics, economics, and public policy at Georgetown University. "It looks essentially like a nonprofit that has the conspicuous benefit of being a great place where people can get access to Clinton and her staff."

Why the appearance of a conflict of interest is bad — even if there’s no proof of a quid pro quo

On Tuesday, my editor Matt Yglesias argued that that there’s an "absence of any clear evidence of actual misconduct."

"Despite very intensive media scrutiny of the Clinton Foundation, we don’t have hard evidence of any kind of corrupt activity," he wrote.

By some criteria, Yglesias is certainly right: There’s no evidence that donors to the Clinton Foundation did anything like buy off Clinton, and there’s no definitive proof that they got access to the State Department because of their donations.

But the money in politics experts argued that these aren't the only standards of wrongdoing by which we can or should judge Clinton. To them, the fact that the Clintons allowed for an appearance of a conflict of interest — that the suspicion could be reasonably raised — is itself a major shortcoming worth criticizing.

"What's so troubling is that these revelations suggest that if you want to see the secretary of state, it helps to make a large donation — that’s the perception this gives," says Larry Noble, general counsel for the Campaign Legal Center.

I struggled with this idea when I first heard it. After all, if we can’t say anything wrong actually occurred, then who should care what the "perception" is from the outside? Isn’t the appearance of a conflict of interest inherently meaningless if it is ultimately just an appearance?

I think Noble’s response to this question is worth quoting in full:

Politicians like to say things like, "I would have given the lobbyist for Exxon a meeting regardless of their donation," and that might be true. But the problem is that it’s impossible to know if the meeting would have happened anyway, if the meeting was given out of a favor, or what. So they don’t get the benefit of the doubt. It’s their job to make sure they avoid the appearance of a conflict in interest in the first place — because if a politician has made a decision that affects a major donor [whose money they want], then it becomes basically impossible to sort out why they did it. It calls into question the decision even if it’s totally legitimate and the best one they could make. That’s why the very idea that access to government depends on how wealthy you are — and how much you give — is so dangerous. What the Clintons did here helps create the impression that if you’re a small-business person who wants to talk to the secretary of state, then you’re out of luck. But if you donate a few million dollars to her husband’s charity, you can talk to her.

In other words: Since it’s so difficult for anyone to ever prove a quid pro quo, it’s incumbent on politicians to recuse themselves so it can’t even look like they’re swapping favors for private donations — or to not take those donations in the first place.

By that standard, Hillary Clinton clearly failed.

Are Clinton’s issues with money in politics unusual?

The specific circumstance of Hillary Clinton serving as secretary of state while her ex-president husband runs a major charitable foundation is unique. But the same experts who tell me they found the arrangement troubling see the Clinton Foundation as an example of a much larger universe of Washington influence peddling, not a case of unique corruption. Whether you like the game or not, this is the way it’s played: Someone cuts a check to a politician and in exchange gets a chance to try to press his or her case.

"This is how you access senior government officials and impact policies and programs; it’s the same reason you hire lobbyists. You want to get facetime or your position papers in the appropriate hands, and the donation can help open the door," says Scott Amey, general counsel at the Project on Government Oversight.

Amey adds: "At the state and local level, too, when donors know an appointee or a senior government official, a lot of emails come in asking, ‘What can you do for me now that you’re in a position of power? So I’m not surprised there was a line of people headed by Mr. Band asking for meetings, favors, or special treatment."

Indeed, a cynic might wonder if there’s any difference at all between the Clinton Foundation and the routine campaign fundraising that every politician does. The answer is that it is somewhat different because, as a private nonprofit, the foundation exists in an entirely different legal framework from campaign fundraising organizations.

Private nonprofits have much looser disclosure requirements, for instance (though the Clinton Foundation went beyond what the law requires on this front), and don’t have really any restrictions on foreign or corporate donations.

"Everyone knows money is involved in politics, but we try to keep parameters around it to make sure it’s fair and transparent," says English, the Georgetown professor. "The foundation appears to be an anomaly, because the Clintons have something outside the parameters from the campaign finance system."

Most money in politics issues are about domestic affairs, not international policy

Most controversies about the role of money in politics revolve around domestic lobbying efforts. But the Clinton Foundation took tens of millions of dollars possibly related to international affairs — and that, too, makes it look substantively different from anything we’ve seen recently, according to the experts I interviewed.

"This is really beyond the mainstream," Biersack said. "It’s one step removed from the normal political back and forth."

The arrangement wasn’t illegal, but Biersack noted that it flies against the spirit of restrictions around what foreign governments can give American officials. The Constitution, for instance, explicitly prohibits the president or the first lady from accepting gifts from foreign countries for this very reason.

English pointed to a recent New York Times exposé detailing how foreign governments had used donations to influence American think tanks like the Brookings Institution. Since these international conglomerates can’t directly contribute to US elections, dumping cash into research institutions that lawmakers rely on represents an alternate route to influence them. The Clinton Foundation looks like a similarly novel way to try to change US government policy while going around campaign finance restrictions, English said.

Even that example, though, didn’t involve money directly flowing from foreign governments to the families’ private foundations, according to English.

"The State Department has always held itself out — almost like the Justice Department — apart from real partisan politics," Biersack said. "The idea that you have foreign governments, and the investment funds of foreign governments, heavily involved in financing an institution that’s this tied to the secretary of state’s family — well, that appears to be something new."