In 1940, Fred Schwed wrote Where Are the Customers' Yachts?, a brilliant assessment of Wall Street people's pledge to look after themselves, first and foremost. If they can make a few pennies for their customers in the process, wonderful. But fees, salaries, and bonuses always come first. Always.

Fast-forward 70 years, and we get this gem, courtesy of Bloomberg:

[Royal Bank of Scotland (NYSE: RBS), JPMorgan Chase (NYSE: JPM), and Barclays (NYSE: BCS)] are charging fees on some structured notes that equal or exceed the securities’ highest possible yield, as sales of the opaque products draw scrutiny from regulators.

On June 15, RBS gave brokers a 2.75 percent commission to sell a three-month reverse-convertible note with a 2.56 percent potential yield, according to a prospectus. Last month, JPMorgan charged 5.25 percent in fees and commissions on a three-month Citigroup Inc.-linked note that paid 5 percent interest, and Barclays offered brokers a 2 percent commission on a security paying 2 percent interest, according to other prospectuses.

Sad. Although not terribly surprising. Las Vegas is built entirely on the concept of innumeracy. The past two years aside, it has been a remarkable success. Same goes for Wall Street.

If you want to ensure a prosperous financial future, listen to the advice of Berkshire Hathaway (NYSE: BRK-A)(NYSE: BRK-B) co-chairman Charlie Munger: "Brokers will sell toxic sludge if the commission is high enough. I tell my kids, 'If anyone tries to sell you something with a high commission, don't let them finish their sentence. Show them the door.' " 

Fool contributor Morgan Housel owns shares of Berkshire Hathaway. Berkshire Hathaway is a Motley Fool Inside Value recommendation and a Stock Advisor selection. The Fool owns shares of Berkshire Hathaway, and has a disclosure policy.