Laws of Lashon Hara, chapter 2, section 12
If someone delivers a talk in a beis hamidrash, halacha forbids one to mock him and say that his talk was worthless and that there was nothing to hear. Through our many sins, many people transgress this and do not consider such mockery as forbidden at all. But according to halacha this is an absolute prohibition, as it causes one's fellow financial damage and pain and embarrassment. Even if this were true, lashon hara is forbidden even about the truth. If one is truly concerned about the speaker, he should discuss the matter with him and point out his mistakes. By giving this advice he will fulfill, "You shall love your fellow as yourself." It is certainly forbidden to make a mockery of him before people.
Laws of Lashon Hara, chapter 2, section 13
If someone revealed to his fellow in front of three people details about his business and trade, and suchlike, that one is generally forbidden to reveal to another person lest this causes harm or pain to the speaker - if he spoke before three people, this indicates that the speaker is not concerned about this. Therefore the listener will be permitted lechatchila to relate it to others, so long as the speaker does not indicate that he is particular about the matter.
