Bill Clinton might have had an extramarital affair with an intern. Conspiracy theory: Keith Richards may have used, at some point in the not-too-distant past, illicit recreational substances. Conspiracy theory: Joe Biden's people might be lying to us about his medical condition and when they knew about it.

The 31st president, Herbert Hoover, had early-stage colon cancer that was diagnosed because of anemia and gastrointestinal bleeding, according to Labroots. Part of his colon was removed and he lived another two years, but died of related internal bleeding.