Hilchos Lashon Hara chapter 6, section 8

. This applies if the person spoken of was an average person who generally does not sin but sometimes does. How much more if the story involved a God fearing person to whom the positive mitzvah of You shall judge your fellow charitably applies even more (as explained in the Rambam, Avos 1, and Rabenu Yonah, maamar 218).