To the best of my knowledge, Luther never had syphilis. He did suffer from depression and from scruples, however; and he also advocated ideas that were a lot odder than
sola fide.
For example, he told the German princes during the Peasant's Rebellion that they could get to heaven faster by slaughtering peasants than they could by prayer; he stated that he could see nothing in Scripture against polygamy; and he advocated violence and hatred against the Jews on a level that would have made Hitler proud.
Not exactly a plaster saint, but then, he never kept a stable of women (a good half of them married, and one of them his own daughter

) for his sexual pleasures---and our very own Roman Pontiff, Pope Alexander VI did.
But Alexander never advocated that everybody should behave exactly as he did.....and Luther apparently did.