Śrīla Bhakti Rakṣak Śrīdhar Dev-Goswāmī Mahārāj describes the distinction between fault-finding and affectionate correction.
Student: Mahārāj, could you elaborate on one point that you made; it was very nice: if we find fault in another person, then that fault will eventually come back to us.
Śrīla Śrīdhar Mahārāj: Yes. That will come back to us. Through our connection with a fault, the influence, the contamination of that fault will come to us. But if like a guardian you want to remove a fault affectionately, then it may not come back to you.
Student: Śrīla Bhakti Vinod Ṭhākur mentioned para-doṣānusandhan [finding faults in others] as being one type of prajalpa or unnecessary talk.
Śrīla Śrīdhar Mahārāj: Generally, the matter of prajalpa, idle talk, becomes para-doṣānusandhan, finding fault with others. But when a guardian analyses his affectionate friend or disciple with a sympathetic and graceful eye and points out a fault to them for correction, then that fault may not come back to him be he pure enough. When a nurse goes to attend an infectious patient, the infection will naturally come to the nurse, but if the nurse is well guarded, then the nursed may not be infected. When a nurse is conscious of the poisonous nature of a disease, then the nurse will try to remove the disease from the body of a patient with a guarded mind and dress, being very careful to avoid becoming infected. So, the poison, infection, may not always come to one who goes to correct the fault in another.
Reference
Spoken 30 August 1981.