I was unhappy earlier today about all the media attention to some Arizona voters who told a focus group that they think Donald Trump is just dreamy. It’s the same old same old form the media who are once again working feverishly to pump up Trump’s popularity. But Philip Bump at the Washington Post had some interesting information that indicates that an Arizona focus group may not have its finger on the pulse: YouGov measures the popularity of past presidents among all Americans. And a pair of professors conducts a survey asking members of the American Political Science Association to evaluate presidential “greatness.” At the upper end of the spectrum, there’s general agreement. Abraham Lincoln is the most positively viewed president among both groups. George Washington and Franklin D. Roosevelt are near the top as well. There’s some deviation on John F. Kennedy, who’s third on YouGov’s list and 10th among the presidential scholars. But that deviation is nothing compared with what happens at the other end of the spectrum. The worst-performing past president among the general public is James K. Polk, to a significant extent because so few Americans have an opinion of him (quite justifiably). Historians, meanwhile, think the worst president on that measure of greatness was … Donald J. Trump. No president has a larger gap between his rankings by the public and by the experts. He’s 20th on the public’s list (one place behind Biden) and 45th on the scholars’. […] The average for Trump’s first term and Biden’s was…