We know that two types of sukṛti can help a bonded soul two different way. One is bhog unmukhi sukṛti and the other is sevā unmukhi sukṛti. With some motive if somebody serving Guru-Vaiṣṇava then he can develop some bhog unmukhi sukṛti because they are vāñchā-kalpa-taru. But without any desire or duplicity if somebody somehow knowingly or unknowingly doing some sevā of Guru-Vaiṣṇava then sevā unmukhi sukṛti can arise. So regarding preaching of Hari-kathā–kīrtana this much we can say that if one madhyama adhikārī Vaiṣṇava going in preaching field to help common people to develop some sukṛti, this is more practical because the following śloka is only applicable for madhyama–adhikārī Vaiṣṇava–
īśvare tad-adhīneṣu
bāliśeṣu dviṣatsu ca
prema-maitrī-kṛpopekṣā
yaḥ karoti sa madhyamaḥ (Śrī Caitanya-caritāmṛta, Madhya-līlā 22.64)
“The madhyama–adhikārī is a devotee who worships the Supreme Personality of Godhead as the highest object of love, makes friends with the Lord’s devotees, is merciful to the ignorant and avoids those who are envious by nature.”
So according to the response given by bonded soul a madhayma adhikārī Vaiṣṇava can find suitable medicine for him.
When one bonded soul in the form of sādhu vesh going into preaching field then due to their bonded condition they cannot seek any benefit either for himself or for others. If at all Nāmābhāsa coming in the form of preaching than still it is ok, but when Nāma-aparādha coming in the form of preaching then what we can expect. Nāmābhāsa can give material mukti, whereas Nāma-aparādha can increase our anartha.
sāṅketyaṁ pārihāsyaṁ vā
stobhaṁ helanam eva vā
vaikuṇṭha-nāma-grahaṇam
aśeṣāgha-haraṁ viduḥ (SB 6.2.14)
One who chants the holy name of the Lord is immediately freed from the reactions of unlimited sins, even if he chants indirectly [to indicate something else], jokingly, for musical entertainment, or even neglectfully. This is accepted by all the learned scholars of the scriptures.
Innocent person having no sense of relationship with Bhagavan as yet, if he/she is going to speak out Hari-nāma somehow according to the above śloka then it can be called Nāmābhāsa, but those who are already having sambandha jñāna from Sad Guru if with some bad motive or desire they going to speak Hari-nāma then it can be treated as Nāma-aparādha.
Gaura Hari Haribol