Whose mother-in-law has a bad reputation?

The reputation of a mother-in-law and a bad daughter-in-law is the worst for a son. Because a daughter-in-law's mother-in-law is her son's mother and daughter-in-law is her son's wife, the bad reputation of her mother-in-law as a daughter-in-law will intensify her son's family harmony and leave a bad reputation for the disharmony between her mother-in-law and her daughter-in-law. The most direct thing is that it is bad for her son.