Wisdom from The Nectar of Instruction by Swami Prabhupada.

When Śrīla Satyarāja Khān, a great devotee of Śrī Caitanya Mahāprabhu, asked the Lord how a Vaiṣṇava could be recognized, the Lord replied:

prabhu kahe,——“yāṅra mukhe śuni eka-bāra
kṛṣṇa-nāma, sei pūjya,——śreṣṭha sabākāra”

“If one hears a person say even once the word ‘Kṛṣṇa,’ that person should be accepted as the best man out of the common group.” (Cc. Madhya 15.106) Lord Caitanya Mahāprabhu continued:

“ataeva yāṅra mukhe eka kṛṣṇa-nāma
sei ta ’vaiṣṇava, kariha tāṅhāra sammāna”

(....)

Those who are innocent but simply carried away by bad association should be shown favor if they are eager to receive proper instructions from pure devotees, but those neophyte devotees who are actually initiated by the bona fide spiritual master and are seriously engaged in carrying out the orders of the spiritual master should be offered respectful obeisances.

Full text : https://prabhupadabooks.com/noi/texts?d=1