California Democratic Sen. Dianne Feinstein is back in the news as the giant real estate investment firm run by her husband, Rich Blum, is possibly poised to earn as much as $1 billion in commissions from selling U.S. Postal Service buildings across the country.

Several years ago, Feinstein said that she exerted no influence in the process that led to Blum’s company, CBRE Group, then the world’s largest commercial real estate services firm, obtaining an exclusive contract to market USPS facilities—as part of a larger federal effort to reduce the deficit.

Feinstein dismissed the conflict of interest allegations at the time, which were followed by numerous investigative reports criticizing the deal. The USPS Inspector General issued a report saying the contract was not how it previously sold properties and was unlikely to reduce USPS costs. California-based investigative reporters found that CBRE was selling properties below market value to clients, which means those buyers could likely profit if they resold them.

“CBRE has been paid commissions as high as 6 percent by the Postal Service for representing both the seller and the buyer in many of the negotiations, thereby raising serious questions as to whether CBRE was doing its best to obtain the highest price possible for the Postal Service,” reported northern California’s East Bay Express.

But now, new reports are saying that CBRE—where Blum was a member of the board and chairman from 2001 to 2014—stands to make possibly $1 billion in commissions from the sale of 56 buildings across the country that are expected to yield upwards of $19 billion.

Whether or not those profit estimates prove to be accurate, this deal is a classic example of what’s legal and corrupt in government contracting. Even if Feinstein’s word is true—that she never lobbied or intervened with the USPS on behalf of her husband—the political world in Washington is like a village where longtime players know everyone else, and favors are implicitly given and taken without explicit approval.

The details of this potentially hugely profitable deal are complex and somewhat slow-moving, which has helped it recede from the headlines. However, longtime politicians like Feinstein should know that its optics—how it appears—are not favorable, just as she likely knows that media scrutiny will come and go.

When the contract was first announced in 2009, the public-interest group CREW, Citizens for Responsibility and Ethics in Washington, called for an investigation, saying it didn’t look like a “fair deal” for taxpayers. The USPS Inspector General’s June 2013 report on the contract confirmed that it was significantly tilted in CBRE’s favor. However, that IG report focused on small issues, such as the initial invoices to the government, and not larger questions of Feinstein's involvement.

Stepping back from this deal, it appears that the political climate in Washington seems incapable of creating sufficient pressure to prompt political spouses to step away from deals leaving public perceptions of insider deal-making.

Indeed, when the U.S. House adopted rules for the new session of Congress, it watered down the rules concerning that body’s ethics investigatory ability—another sign that Congress really doesn’t want to change the way Washington operates.

That’s why the real scandals in Washington are often what’s legal—not illegal.