Mishnayos Kesuvos Perek 7 Mishnah 10

And these are the defects for which the court forces him to divorce her: One afflicted with boils; or one who has a polyp; or one who works as a gatherer, or one who works as a melder of copper, or one who works as a tanner of hides, all of whose work involves handling foul-smelling materials. Whether he had these defects before they got married, or whether they developed after they got married, the court forces them to divorce. And with regard to all of these, Rabbi Meir said: Even though he stipulated with her ahead of time that he suffers from this particular ailment or this is his line of work, she can nevertheless demand a divorce and say: I thought I could accept this issue but now I realize I cannot accept it. And the Rabbis say: If she initially agreed she must accept it against her will, apart from a situation in which her husband is afflicted with boils. In that case the Rabbis concede that he must divorce her, because the disease consumes his flesh when they engage in marital relations. The mishna relates an additional account: An incident occurred in Sidon involving a certain tanner who died childless, and he had a brother who was also a tanner. This brother was required to enter into levirate marriage with the widow. The Sages said: She can say: I could accept living with a tanner for your brother but I cannot accept it for you, and therefore he must perform ḥalitza with her.