Tractate Ketubot - Chapter 7 - Mishnah 10 כתובות פרק ז׳ משנה י׳

These are the ones who are forced to divorce [their wives]: one who is afflicted with boils, one who has a polypus, a gatherer [of dog feces for the treatment of hides], a coppersmith or a tanner whether they were [in such a condition] before they married or whether they arose after they had married. And concerning all these Rabbi Meir said: although the man made a condition with her [that she accept him despite these defects] she may nevertheless say, “I thought I could accept him, but now I cannot accept him.” The Sages say: she must accept [such a person] against her will, the only exception being a man afflicted with boils, because she [by her intercourse] will enervate him. It once happened at Sidon that a tanner died, and he had a brother who was also a tanner. The Sages said: she may say, “I was able to accept your brother but I cannot accept you.”