It’s worth noting that one ‘serious’ attack on Peary came in 1989, when the Washington Post printed ‘newly unsealed’ observations that showed Peary more than 100 miles from the North Pole. The article made it sound like Peary had intentionally hidden these numbers, and had designed for them to be uncovered years after Peary’s death.
Unfortunately, the Washington Post took one guy’s research at face value without enough critical thinking: http://www.pearyhenson.org/polarcontroversy/rawlins.htm
More unfortunately, the story has lingered - I think most people who don’t believe Peary was first have never heard the debunking of the Peary’s ‘faked sextant readings.’