Why is contempt seen as potentially lacking in the respect for persons and therefore prima facie subject to negative moral evaluation? This paper starts by looking at a distinctive feature of contempt in the context of thick relationships, such as those of friendship, close professional collaboration, or romantic love: there is an irreversibility effect attached to the experience of contempt. Once contempt occurs in a thick relationship, it seems very difficult to return to non-contemptuous reactive attitudes. The second part argues that the irreversibility effect is due to the fact that contempt is an affective attitude which tends to invisibilize the person who is the object of contempt. The tendency to invisibilize is inscribed in the intentional structure of contempt as well as in its motivational dimension. The final part explores some consequences of this hypothesis, and in particular argues that it also explains why contempt motivated by abject wrongdoing, as opposed to resentment, anger, or hatred, tends to block any process of forgiveness.