ChofetzChaimDaily 11 Cheshvan 4:1 Asur to degrade someone about their parents negative actions, or their own past misdeeds. Even if someone is actively doing something wrong bein adam laMakom, asur to tell anyone about it. 4:2 Asur even if its a slight wrongdoing i.e. not keeping a minhag etc.
ChofetzChaimDaily 10 Cheshvan 3:7 One is obligated to judge his fellow favorably as it says, Bitzedek tishpot amisecha, often, not doing so leads to LH (see sefer for more detail). 3:8 Even in scenario that one isnt obligated to judge favorably, one still must not relate what he saw, unless the conditions are met. See chap 4, 5, 10.
ChofetzChaimDaily 9 Cheshvan 3:5 Asur to say LH in a sneaky fashion, i.e. to make believe one doesnt realize that what hes saying is negative, or that ploni acts this way 3:6 Asur to say LH even if you know in advance that it wont cause any harm to the subject.
ChofetzChaimDaily 8 Cheshvan 3:3 Asur to degrade someone even if said as a joke. 3:4 Asur to say anonymous story, if the listener will be able to discern who youre saying bad about. Asur to cause a negative impression about somebody, no matter how you accomplish that.