Real Monk vs Fake Monk

Just as the Buddha referred to those who achieved the goal as "My Son", I am wondering if the Buddha made any similar distinctions between monks who lived by the precepts and practiced according to the teachings, and those who were there for reasons of their own, not in line with the teachings of the Buddha? Did he give any teachings on how to deal with monastics who abuse their position for unwholesome motivations i.e. monks amassing wealth, gaining political influence, acting as antagonists for violence. Just as high-profile leaders in other religions have given their respective faith a tarnished reputation with shady dealings in the past, is there anything to be done to protect the dignity of the Buddhas teaching from those with less than wholesome intentions?