Jayapataka Swami explains Prabhupada's teaching that ISKCON preachers must be spotless in character. Even a small moral failing, like a drop of ink on white cloth, damages public trust and undermines preaching, which depends entirely on faith and respect.
Chapters
He followed the strict principle that a preacher cannot preach unless his character is spotless. A little spot on a preacher's character. Examples give us like a piece of a drop of ink on a white sheet. Everyone will see it immediately. Unless. Thasa Prabhupada repeatedly advised us that for us to preach anywhere in the world, we have to have a good respect in those areas. If we act in such a way that people distrust us, then it's very difficult to preach, because preaching is all a matter of faith. To some degree. Of course, Ka consciousness has the maximum amount of scientific understanding, systematic presentation, even logical and beyond logical understandings. But nonetheless, if a person has already got it in his mind that, well, this person is not to be trusted, then no matter what you say, even if it makes sense, it's very hard to convince someone of something because they won't really listen. So for a preacher, it's essential that his character should be held in great esteem. Maharaj Prabhupada Rather, he advises that his desire was that everyone should understand and see ISKCON devotees as the most honest, that they shouldn't do anything dishonest, which would hamper the good respect of the people.