He did not mention how easy it had been to get that title.

He had paid $1,095 for a correspondence course, then took a multiple-choice exam with questions like, “Marketing can best be described as:” (The answer: “The process or technique of promoting the sale or distribution of a product or service.”) Like more than 18,700 other applicants since 1997, he passed.

Insurance companies, eager for sales representatives, embraced Mr. DelMonico, as they have thousands of other newly credentialed advisers.

The following year, insurers paid him commissions worth $720,000 as his business with retirees soared.

But many of those sales came from steering older Americans into unwise investments, Massachusetts regulators contend in a lawsuit.

Mr. DelMonico denies all wrongdoing, but one of his clients — a 73-year-old widow caring for a son with Down syndrome — said he tricked her into buying complicated insurance contracts that left her unable to pay dental and home-repair bills.

“His office was filled with things saying he was certified to help seniors,” said that client, Mary Ann St. Clair. “The only one he really helped was himself.”

Mr. DelMonico is one of tens of thousands of financial advisers working hand-in-hand with insurance companies to market themselves to older Americans using impressive-sounding credentials like “certified elder planning specialist,” “registered financial gerontologist,” “certified retirement financial adviser” and “certified senior adviser.”

Many of these titles can be earned in just a few days from for-profit businesses, and sound similar to established credentials, like certified financial planner, that require years of study, difficult tests and extensive background checks.

“The degree isn’t worth the paper it’s written on,” said T. Kevin McElreath, a financial adviser in Milford, Mass., who took the certified senior adviser exam but does not use the credential. For many agents, he said, “it’s a scam, a way to put a title on a business card that impresses gullible seniors.”

Many graduates of these short programs say they only want to help older Americans. But they are frequently dispensing financial counsel they are unqualified to offer, advocates for the elderly say. And thousands of them are paid by some of the country’s largest insurance companies — including Allianz Life, Old Mutual Financial Network and American Equity Investment Life Insurance — to sell elderly clients complicated investments that economists say most retirees should never own.

The prize for these insurers and sales agents is a piece of the $15 trillion held by Americans 65 and older, the largest pool of assets ever amassed by an aging population, according to the Government Accountability Office.

As older Americans’ wealth has grown, so too have programs that offer quickly earned credentials or that teach agents how to sell to the elderly. The number of certified senior advisers has increased by 78 percent in the last five years. More than two dozen such programs now exist, and have enrolled more than 39,000 people over the last decade. As more baby boomers retire, the number of programs and enrollees is likely to grow significantly, analysts say.

But some of the existing programs, which are often linked to insurance companies, have taught agents to use abusive sales techniques, regulators say.

The insurers Allianz, Old Mutual and American Equity have been listed as sponsors at seminars with names like the Million Dollar Academy, where thousands of sales representatives were advised to scare retirees by saying, “I am all that stands between you and potential catastrophic loss.” Other seminars instructed agents to “drive a wedge” between retirees and their established advisers.

“The insurers are happy to turn a blind eye to what salesmen are doing, as long as they make a sale,” said Minnesota’s attorney general, Lori Swanson, who is suing several companies, including Allianz, contending their products are inappropriate.

Allianz, Old Mutual and American Equity, whose revenues last year were a combined $163 billion, said they investigate the backgrounds of all agents, screen all sales to consumers to make sure they are appropriate, and have terminated representatives using improper sales methods. Those companies said they were not aware of abusive methods taught at any seminar they endorsed.