Hilchos Lashon Hara chapter 5, section 2

I will now discuss a type of lashon hara where the speaker has no intent for any benefit but only wants to disparage someone. Almost everyone transgresses this type of lashon hara out of ignorance.
It is forbidden to disparage a person for lack of positive traits such as wisdom or strength, for example, to say that someone isn’t smart. This is obviously forbidden when what says is false or exaggerated and even worse than regular lashon hara as false disparagement counts as motzi shem ra. Even if the information is true, we already proved in chapter 1 that lashon hara includes even saying the truth. As the Rambam (Avos 1:17) writes, “Lashon hara is to speak of the bad of a person and his flaws and to disparage him with some sort of disparagement even if the disparaged person indeed lacks, etc.” Even though he writes (Deós 7:5) that lashon hara is only that which causes financial or physical damage, or sorrow or fear to the victim, it is clear that disparaging people counts as lashon hara forbidden by the Torah since such words can always cause the victim financial or physical harm.
For example, there is no greater disparagement than saying that someone is unwise as people won’t want to take him as a son-in-law or deal with him in his profession. Certainly, if the victim is a poseik he will lose money as no will go to him to settle financial disputes and he may even lose his position, causing harm to him and his children. Furthermore, this is categorized as disparaging a Torah scholar concerning which the sages say there is no cure to his punishment. Also, this greatly lowers the honour of the Torah for if the poseik warns people to observe mitzvos they will ignore him after people said he is not wise.