Voters haven’t heard much about it, but Newt Gingrich hasn’t exactly held a real job in a very long time. He has, however, overseen a very lucrative enterprise often called “Newt Inc.”

Gingrich, you’ll recall, was forced to resign from Congress in disgrace way back in 1998, after his fellow Republicans decided they no longer had use for his kind of “leadership.” In the 13 years since, the former House Speaker hasn’t held or sought public office at any level.

What’s he been doing? Karen Tumulty and Dan Eggen take a look today at the “business conglomerate” Gingrich put together after his political career was left in shambles.

The power of the Gingrich brand fueled a for-profit collection of enterprises that generated close to $100 million in revenue over the past decade, said his longtime attorney Randy Evans.

Among Gingrich’s moneymaking ventures: a health-care think tank financed by six-figure dues from corporations; a consulting business; a communications firm that handled his speeches of up to $60,000 a pop, media appearances and books; a historical documentary production company; a separate operation to administer the royalties for the historical fiction that Gingrich writes with two co-authors; even an in-house literary agency that has counted among its clients a presidential campaign rival, former senator Rick Santorum (R-Pa.).

Separate from all of that was his nonprofit political operation, American Solutions for Winning the Future. Before it disintegrated this summer in Gingrich’s absence, American Solutions generated another $52 million and provided some of the money that allowed the former speaker to travel by private jet and hired limousine.

Along the way, Gingrich has become a wealthy man, earning $2.5 million in personal income last year, according to his financial disclosure form.

It’s not altogether clear what, exactly, Gingrich has done with his days. He’s been paid handsomely for his “strategic advice,” which the disgraced former Speaker insists was not technically lobbying. Gingrich has also given plenty of speeches, made near-constant appearances on television, and adopted a rather luxurious personal lifestyle, but in terms of actual work, the record appears to be pretty thin.

In any case, while the Post‘s piece is a good one, the one thing it doesn’t fully convey is just how sketchy — and at times, even sleazy — Gingrich’s operation has been.

As part of his shady financial empire, for example, Gingrich ran a dubious direct-mail scheme, offering to name random businesspeople as “entrepreneur of the year” in exchange for a $5,000 “membership fee” to Gingrich’s American Solutions for Winning the Future.

In one rather amusing example, Gingrich offered to name a strip-club owner as “entrepreneur of the year” for $5,000. When the nude-dancing entrepreneur accepted, Gingrich’s embarrassed staff canceled the 2009 award and returned the money — only to hit the exact same strip-club owner up for more cash two years later.

It wasn’t an isolated incident. Gingrich has overseen all kinds of entities, all of which have raised a lot of money over the last several years, without much to show for it. Not surprisingly, the whole operation has drawn some quizzical looks.

[C]onsumer advocates and some disgruntled donors have raised questions over the years about Gingrich’s seeming penchant for aggressive tactics, including the heavy use of fundraising polls, blast-faxes and other techniques considered unsavory or even predatory by philanthropy groups. […]

According to complaints on consumer-focused Web sites, some American Solutions calls begin with slanted polling questions before proceeding to a request for money. The tactic, known as “fundraising under the guise of research,” or frugging, is discouraged as unethical by trade groups such as the Marketing Research Association.

American Solutions also has drawn criticism because it spends nearly $2 on fundraising for every $3 it brings in — about twice the figure for many nonprofit groups, experts said.

Given the fact that Gingrich was plagued by ethics scandals during his congressional tenure, coupled with his business ventures over the last 13 years, it’s hard to have much confidence in this guy’s sense of propriety.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.