Gaudiya Gosthi Pati Sri Srila Bhakti Siddhanta Sarasvati Gosvami Thakur Prabhupada very often used to speak the following sloka from shastra—
sri-bhagavan uvaca
para-svabhava-karmani
na prasamsen na garhayet
visvam ekatmakam pasyan
prakrtya purusena ca
The Supreme Personality of Godhead said: One should neither praise nor criticize the conditioned nature and activities of other persons. Rather, one should see this world as simply the combination of material nature and the enjoying souls, all based on the one Absolute Truth. (SB 11.28.1)
For bonded souls it is strictly prohibited to criticize or praise others, because for criticizing or praising one has to concentrate on the object concerned. Anyway- any object or any man of this guna moy jagat (material world) is an object of Maya, so naturally if someone going to criticize or praise any object or any man then surely he is bound to lose his concentration on the absolute object—Supreme Lord, which is very dangerous for a bonded soul, because death can come any moment. If someone going to leave body with material conception of Maya ( Illusion) then it is very dangerous. We know the following instruction of Srimad Bhagavad Gita 8.6:
yaṁ yaṁ vāpi smaran bhāvaṁ
tyajaty ante kalevaram
taṁ tam evaiti kaunteya
sadā tad-bhāva-bhāvitaḥ
“Whatever state of being one remembers when he quits his body, O son of Kuntī, that state he will attain without fail.”
Pure Guru-Vaishnav out of their love &affection sometime become bound to speak or write heavily to check the downfall of the situation in which bonded souls are put into, but for that they are not going to suffer any result, because it is the sole duty of Guru-Vaishnava to get control over the painful situation of this world. If sat Guru-Vaishnava not going to indicate us our good or bad then who can teach us. Their chiding is one kind of genuine affection.
Gaura Hari Haribol