Hilchos Lashon Hara chapter 5, section 3 4

. If your evil inclination tries to persuade you that this is not lashon hara, consider. If someone said such things about you, how angry you would be! You would say: What signs of foolishness did I display? The person spoke against me out of viciousness. If so, how can you say such things about someone who may be even better than you?
Indeed, this sort of lashon hara is worse that speaking of someone’s wrongdoings for a number of reasons. First, if one says someone sinned one may be motivated by the hatred of sin even though this is no excuse to speak lashon hara as we said in chapter 4:2 and paragraph 1 of this chapter. But in the case of disparagement one’s intent is purely evil.
Furthermore, people do not easily accept regular lashon hara. Many say: I will not believe this unless I see it with my own eyes. Also, even if what you said is true the person probably did it because of some reason. He wouldn’t have sinned for no cause. In addition, if it turns out that the story of someone sinning was false the speaker will be held in contempt for lying about someone. But when it comes to disparaging people few listeners object and it is as if the speaker did nothing wrong. As the verse says, She eats and wipes her mouth and says, I did no iniquity (Proverbs 30:20).
What we said applies even if one says that a person is unwise in worldly matters, and how much more if one says of someone considered as knowing the Torah that he only knows a little for this can cause him harm or at least pain.
One example of this is to say that a town rabbi is not a Torah sage but only knows necessary, practical halachos, or to say this of a newly married person. I cannot mention every possible disparagement but, Give to a wise man and he will add wisdom (Proverbs 9:9). The same applies if one says that a craftsman is incompetent. If one’s intent is for a positive purpose we will discuss this later in chapter 9 of the laws of Rechilus.