Advice should be given only by a Pure Vaisnava
The Lord has given perfect advice in Bhagavad-gita, and Ambarisa Maharaja, as the ideal executive head, ruled the entire world as a Vaisnava, taking advice from Vaisnava brahmanas.
The sastras enjoin that even though a brahmana may be well versed in the occupational brahminical duties and may be very learned in Vedic knowledge, he cannot give advice as a guru until he is a Vaisnava.
sat-karma-nipuno vipro mantra-tantra-visaradah avaisnavo gurur na syad vaisnavah sva-paco guruh Therefore, as indicated here by the words tan-nistha-viprabhihitah, Maharaja Ambarisa took advice from brahmanas who were pure devotees of the Lord, for ordinary brahmanas who are merely learned scholars or experts in performing ritualistic ceremonies are not competent to give advice. SB 9.4.21
Only a Vaisnava is qualified to give advice as a guru and if we see the definition of Who is a Vaisnava? We get to know that the definition of who is a Vaisnav by our our predecessor ‘ Acharyas including Srila Prabhupada have given the definition of a Pure Vaisnava and not mixed Vaisnava.
Please refer our previous mail on Who is a Vaisnava?