Who are “they”?

That’s the question I often ask people when they want my opinion about some financial advice they’ve heard. Here are some of the things “they” say:

Getting student loans is a good thing because it’s an investment in your future.

Now’s the time to get a home because interest rates are low.

Never pay off your mortgage, or you should keep a mortgage for the tax break.

It’s better to pay off the debt by borrowing from your 401(k) retirement savings account because you will be paying yourself back.

My question about who “they” are often solicits chuckles because people realize that in their effort to help themselves, they’ve picked up pieces of advice from biased individuals or without doing the work to figure out if it’s prudent.

Millions of consumers have been duped by people — many once touted as icons — who turn out to be charlatans or who gave advice that they themselves didn’t follow, says Zac Bissonnette, a personal finance writer.

Time and again, we learn that self-help authors have become wealthy, not by following their own advice, but by selling the concept of a certain life or financial enriching strategy. We’re reminded that politicians, corporate and religious leaders, entrepreneurs, sports figures and relationship experts are not practicing what they preach. It’s these folks that Bissonnette criticizes in “Good Advice from Bad People: Selected Wisdom from Murderers, Stock Swindlers and Lance Armstrong” (Portfolio/Penguin, $15). It’s my pick for this month’s Color of Money Book Club. The murderers include cult leader Jim Jones and Gary Shawkey, who was given a life sentence for killing a 71-year-old investor he bilked out of $1.2 million. His self-published book was titled “If I Can … Anybody Can … “

I couldn’t stop shaking my head as Bissonnette took me down memory lane, starting with the financial arena.

Remember the Beardstown Ladies?

They were part of an investment group from Beardstown, Ill., who wrote the bestselling “The Beardstown Ladies’ Common-Sense Investment Guide: How We Beat the Stock Market and How You Can Too.”

Along with some recipes for stew and chicken, we were told that from 1984 to 1993, the ladies had an average annual investment return of 23.4 percent. Their book sold almost 800,000 copies.

But some number crunching from journalists and an eventual audit found the ladies hadn’t beaten the market or most money professionals. Their actual return during the time period had been 9.1 percent, compared with the 15.7 percent average annual return on the Dow Jones industrial average.

The women said it was a miscalculation. Their publishing company was sued. There was a settlement and now we have a good lesson about the importance of vetting people’s investment claims. While you can learn a lot in an investment club, “the ladies would probably be better off if they’d just put their money in time-proven mutual funds,” Bissonnette writes.

In the not-so-distant past, we had the falling of another “they” in Bernie Madoff. The once-prominent member of the securities industry and the chairman of Nasdaq is serving a 150-year prison term for bilking investors out of billions.

“And yet, when he actually took a moment to give personal finance advice after his fall from grace, he provided wisdom that everyone should follow: low-cost index mutual funds are the best option for most investors,” Bissonnette writes.

Bissonnette also introduces Angelo Mozilo, the former chief executive of Countrywide Financial. Although the company was approving risky home mortgages, in an email that Bissonnette points out, Mozilo wrote that the no-money-down subprime loan is “the most dangerous product in existence and there can be nothing more toxic.”

But many borrowers listened to the “they” who said homes would increase in value exponentially so that they could refinance out of the risky loans Mozilo and others they were peddling.

Then there is the story of Jesse L. Jackson Jr., the former Democratic congressman from Illinois who is serving prison time for using $750,000 in campaign funds for personal use, including buying Michael Jackson memorabilia.

Bissonnette pulls out this quote from a book Jackson wrote with his father, the Rev. Jesse L. Jackson: “Living above your means is financial sin.” Their book was titled “It’s About the Money!: How You Can Get Out of Debt, Build Wealth, and Achieve Your Financial Dreams.”

Says Bissonnette, “All too often, America’s smiling, inspirational prophets turn out to be comically — and sometimes darkly — horrible at following their own leads.”

I’m sure plenty of people might take issue with some of Bissonnette’s selections of “bad people.” But his book will at least make you pause before you start a sentence with, “They say.”

Michelle Singletary: michelle.singletary@washpost.com.

Washington Post Writers Group

Online chat

Michelle Singletary will host a live online discussion about Zac Bissonnette’s “Good Advice from Bad People” at 9 a.m. Pacific on May 29 at washingtonpost.com/discussions. Bissonnette will join her. Let’s talk about the advice you took that turned out to be bad. Send your comments to colorofmoney@washpost.com.