How can you tell the good ones from the bad ones?
How can you tell good people from bad people?
As you must have found in your own experience of life, it isn't always easy. One of the skills of many bad people is the ability to charm and deceive.
People who are called to a higher station are not always what they should be, including policemen, politicians, judges and even clergy. At the end of the day, they are still people.
Let's remember, a full one twelfth of Jesus' hand chosen was corrupt and evil. It just goes you can't blindly let your guard down with any mortal soul.