What is the ruling on the imamate of one who smokes cigarettes or shisha, or who grows his hair long, and is it permissible to pray behind them?

The prayer led by a congregational imam is valid even if he shaves his beard, smokes cigarettes or shisha, or is effeminate, because he is a Muslim. However, it is an incomplete prayer. It is more befitting that the people be led by the one among them who is most skilled in reciting the Book of Allah and most knowledgeable in the religion, for the Prophet, peace and blessings be upon him, said: "The people are led by the one among them who is most skilled in reciting the Book of Allah." Imam Ahmad also mentioned: "Whoever leads a people while there is someone better than him among them, they will continue to be in decline."