Two of them were from companies that have boasted the Trump name.

One was Trump University, the real estate sales seminar that Donald J. Trump promoted as a way for average people to profit from opportunities in the housing market. Ms. Lankford said she spent $35,000 from an Army insurance payment to learn Mr. Trump’s secrets.

Another was Cambridge Who’s Who, a vanity publisher promising “branding services” that seemed to complement the real estate business she hoped to create. She paid thousands of dollars to Cambridge, whose spokesman and “executive director of global branding” was Mr. Trump’s eldest son, Donald Jr.

Six years later, Ms. Lankford, who is 44 and has a son, has little to show for the money she spent, aside from a nagging sense that she was taken advantage of. Several friends in her community in San Antonio fell for similar offers, she said, but most are not eager to talk about it.

“As a widow, you find you were so dependent on your husband, and when you make a mistake because of predatory businesses, it’s embarrassing,” Ms. Lankford said. “We’re an easy target.”

“Easy target” might describe the audience for several enterprises stamped with the Trump brand that have been accused of preying upon desperation, inexperience or vanity. Some are well known. Trump University has most recently gained notice because of Mr. Trump’s attacks on the Mexican heritage of the judge overseeing a fraud lawsuit brought by former students. There was also a multilevel vitamin-selling enterprise, the Trump Network, that Mr. Trump had said would give hope to people looking to “opt out of the recession.”

But intersecting with these was another, largely unexamined, business venture, Cambridge Who’s Who, which generated hundreds of complaints that it deceptively peddled the promise of recognition in a registry, as well as branding and networking services of questionable value. Dozens of people who paid Trump-endorsed businesses were also sold products by Cambridge, which benefited from its partnership with Donald Trump Jr. through “leveraging relationships built by the Trump empire,” according to Cambridge.

The spending raised eyebrows among campaign finance experts and some of Mr. Trump’s critics who have questioned whether the presumptive Republican nominee, who points to his business acumen as a case for his candidacy, is trying to do what he has suggested he would in 2000 when he mulled making an independent run: “It’s very possible that I could be the first presidential candidate to run and make money on it.”

He could end up turning a profit if he repaid himself for the campaign loans,” said Paul S. Ryan, a campaign finance expert with the Campaign Legal Center. “He could get all his money back plus the profit margin for what his campaign has paid himself for goods and services.”

While most candidates list an array of vendors providing goods and services on their filings, Mr. Trump’s is packed with payments to his various clubs and buildings, his fleet of planes and his family. The self-proclaimed billionaire is required by law to account for his spending this way to prevent his companies from making illegal corporate donations to his campaign. In 2015, about $2.7 million was paid to at least seven companies Mr. Trump owns or to people who work for his real estate and branding empire, repaying them for services provided to his campaign.

As the Huffington Post’s Christina Wilkie reported Tuesday morning, Trump’s campaign spent more than $1 million of that money on Trump companies’ products and services last month, “for facilities rental, catering, monthly rents and utilities at more than a half-dozen Trump-owned companies and properties.” The amount “includes nearly $350,000 that the Trump campaign paid a Trump-owned company, TAG Air, for the use of Trump’s private jets and helicopters.”

That means that every penny of the next $45.7 million in donations to the Trump campaign could literally go directly to Trump’s personal bank accounts before this is all over.

Donald Trump, who has a track record of vowing he’ll do things and then not doing them, vowed Thursday to reopen his controversial Trump University, which is at the center of multiple lawsuits.

“After the litigation is disposed of and the case won, I have instructed my execs to open Trump U,” he tweeted. “So much interest in it!”

Much of that interest is the result of a federal judge in San Diego this week releasing nearly 400 pages of documents related to two of the lawsuits — filed by former students who allege that Trump University duped people with bogus, get-rich-quick promises of making a killing in the real estate market.

Trump says he did nothing wrong and that the majority of people who signed up for his training were pleased with the results. His campaign issued a statement this week saying that “the court’s order unsealing documents has no bearing on the merits of Trump University’s case.”

Did he commit fraud? Take a look at the text of a newspaper ad that ran in these pages in 2007. It quoted a tough-looking Trump as saying that “investors nationwide are making millions in foreclosures … and so can you! I’m going to give you two hours of access to one of my amazing instructors AND priceless information … all for FREE.”

What’s clear from the newly released documents in the federal cases is that even if Trump University students weren’t deliberately fleeced, one of Trump’s top priorities was to separate them from as much cash as possible – regardless of the amount they might actually have available.

“If they really believe in you and your product, they will find the money,” the school’s salespeople were told.

Many of the unsealed documents were instructional “playbooks” intended to guide Trump University employees in closing a sale with prospective students. Trump’s lawyers had tried to keep the materials under wraps.

“When you introduce the price, don’t make it sound like you think it’s a lot of money,” one playbook advised. “If you don’t make a big deal out of it, they won’t.”

It emphasized that salespeople need to size up prospective students for how big a payout they’d be good for – “Are they a single parent of three children that may need money for food?” – and identify those “most likely to buy.”

New York Atty. Gen. Eric Schneiderman, who has brought a separate civil action against Trump, said in a statement Wednesday that the playbooks show “Trump University was a fraud that harmed thousands of individuals.”

The California lawsuits allege that Trump’s “hand-picked” instructors failed to impart any true secrets to real estate success and that the school misled people about the ease with which money could be made off foreclosed properties.

And here’s a fun fact: My name appears in both of the California actions.