From snake oil to gasoline: Ads that stretched the truth

Most false or misleading advertisements contain claims of health benefits that just can't be proven. Originally, snake oil was used to treat wounds by native Americans. For European settlers in the late 19th century, it became a generic name for elixirs that promised to cure all ills. Peddlars of such tonics, skilled in rambunctious hype, later became a stock character in US film Westerns.

Lydia E. Pinkham was an astute saleswoman, marketing successful "women's tonics" even after her death. She began brewing home remedies that were popular among neighbors and friends. Eventually, a thriving family business started. Pinkham answered letters from customers and ads urged people to write in with queries. They received personal replies from Pinkham decades after she died in 1883.

William Frederick Koch was a US doctor who, in the 1940s, claimed his creation - glyoxylide - could cure a long list of diseases that included cancer. He had learned the principles of homeopathy and claimed that glyoxylide was effective at a dilution of one part per trillion. Patients paid up to $300 for a single injection. The US Food and Drug Administration called him a "quack."

Named after pioneering English doctor Joseph Lister, the alcohol-based Listerine was the first over-the-counter mouthwash to be sold in the US. The firm claimed that the product reduced the chances of catching a cold by a half and, in the 1950s, it was even promoted as a cure for dandruff. In 1976, the FTC found Listerine had "no efficacy" in preventing customers from catching a chill.

Will Keith Kellogg was putting nutrition labels on foods in the early 20th century, when the Battle Creek Toasted Corn Flake Company became the Kellogg Company. In 2010, the company agreed to new advertising restrictions after authorities deemed its claim that Rice Krispies could boost children's immunity by 25 percent to be "dubious."

The US Federal Trade Commission (FTC) challenged Dannon over a national ad campaign that appeared to claim Activia's Dan Active could relieve temporary "irregularity" and that it helped to prevent colds and flu. Dannon agreed to settle and was hit with a hefty bill for damages.

The makers of artificial sweetener Splenda claimed their product was "made from sugar so it tastes just like sugar." They were sued by Merisant, makers of rival brand Equal, who claimed it misled customers into thinking the product was natural and more healthy. It might sound like a case of sour grapes, but a French court awarded damages to the plaintiffs and told Splenda to change its ads.

Amoco was originally founded as Standard Oil in 1889 by John D Rockefeller and became a familiar name at US gas pumps. In 1996, the FTC ruled that a campaign for its "Crystal Clear Ultimate" fuel was misleading. Amoco claimed refinement meant its gasoline delivered improved engine performance and environmental benefits. The FTC found no scientific evidence for this.

Having promoted its vehicles as less polluting, VW now faces claims of deceptive advertising. The firm has a history of successful, sometimes iconic commercial campaigns. Its "Think Big" series of ads, dreamed up in the late 1950s was lauded as one of the best campaigns of the century. The company has also long played up its green credentials. Investigators will now decide if it went too far.