Listerine
This product claimed to be as effective as flossing at fighting tooth and hum decay. In 2005 a federal judge ordered the maker at the time Pfizer, to retract the advertisements claiming this.
Q-Ray Bracelets
Product claimed to provide immediate pain relief from chronic pains such as arthritis.
Unfortunately there was no scientific evidence to support these claims and as of 2011 refund checks were supplied by the Federal Trade Commission
Nivea
Claimed that regular use significantly reduced body size. After the FTC took them to court they had to retract their advertisements and pay $900,000 as part of a settlement.
Norelco clean water machine
Claimed to make tap water clean or cleaner. A judge found that this company actually knew they were adding a chemical from cemment that has cancer causing potential.