Excerpt from Kiplinger Personal Finance: "As a television personality, however, Oz has a spotty record and a penchant for pushing unproven products. One study in the BMJ journal found that less than half of the products he promoted on his show were medically proven and 13% contradicted known medical advice."

Columbus gave advice saying the earth was round when 95%+ of the "known scientific advice" said it was flat.  

"On a nationwide U.S. survey [POLES 2021], around 10 percent of respondents agreed with conspiracy claims that the Earth is flat, NASA faked the Moon landings, or COVID-19 vaccinations implant tracking microchips."