A wrong act committed by a servant leads people in general to blame his master, just as a spot of white leprosy on any part of the body pollutes all of the skin.
A Vaiṣṇava, therefore, should be fully qualified. As stated in the Bhāgavatam, anyone who has become a Vaiṣṇava has developed all the good qualities of the demigods. There are twenty-six qualifications mentioned in the Caitanya-caritāmṛta. A devotee should always see that his Vaiṣṇava qualities increase with the advancement of his Kṛṣṇa consciousness. A devotee should be blameless because any offense by the devotee is a scar on the Supreme Personality of Godhead. The devotee’s duty is to be always conscious in his dealings with others, especially with another devotee of the Lord.
(Śrīmad-Bhāgavatam 3.16.5, Translation and Purport)