If our discussion of Most Hated Presidents’ Wives isn’t restricted to U.S. presidents, I’d say more people had it in for Evita Peron than for any other first lady in history.
(Of course, if Andrew Lloyd Webber and Tim Rice are to be believed, Evita was well-loved by most Argentinians – just not the Army or the Upper class.)
As for published slander upon the First Lady, I’m hard pressed to think of any other than the pervasive attitude (amongst some) that she was pulling her husband’s strings (much in the same way Nancy Reagan and Hillary Clinton are likewise accused).
Ellen Wilson? Would that be Wilson’s first wife? If so, I think she just played the ‘good wife’ role and stayed silent; Edith Galt Wilson (Wilson’s second wife) was a major behind-the-scenes player, but kept herself completely out of the limelight, and therefore avoided general scorn.
Of course, I may have the two Wilson wives completely mixed up. My apologies if I do.