Krsna says, api cet su-duracarah. Even though you find in some devotees some bad behavior, not standard, but because he is a devotee, he is constantly engaged in Krsna consciousness, therefore he is sadhu. Even though he has got some bad habits due to his past life, it doesn't matter. Because this will stop. Because he has taken to Krsna consciousness, all nonsense habit will stop. The switch is off. As soon as one comes to Krsna , the switch which impelled one to bad habits, that becomes off immediately. So just like there is heat, Krsna , heater, electric heater. If you make the switch off, it still remains hot, but gradually, the temperature comes down and it becomes cool.
Lecture on Bhagavad-gita 10.8, New York, January 7, 1967