Is it permissible to pray in congregation at home with one's family if the imam of the mosque is characterized by tale-bearing and bad manners?

The bad manners of an Imam are not an excuse to abandon congregational prayer. However, he should be replaced if he is a backbiter, because backbiting is a major sin that leads to فسق (disobedience/impiety). An Imam should be a good role model, and a backbiter does not deserve the Imamate. Furthermore, his prayer is threatened with non-acceptance if people genuinely dislike him, as the Prophet, peace and blessings be upon him, said: "Three whose prayers do not rise above their ears: ... and the Imam of a people who dislike him."