Srila Bhaktisiddhanta  Sajana Toshani (18.2.13-14)
After the time of Sri Caitanya Mahaprabhu, those faithful to Him kept apart from non devotees, to avoid contamination. Seeing this, the personality of Kali sent his representatives in disguise to pollute the Vaisnava sampradaya. Posing as Vaisnavas, they spread their wicked doctrines, and appeared so intelligent and devoted that only pure devotees could detect their real identity. “
 
(Which Srila Prabhupada has so kindly pointed out in his talks and books-for our benefit-but if we dont read or hear them-then what??)
 
Śrī Guru-Tattva and the Secret of Dīkṣā (By: Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura Prabhupāda)
 
Sri Guru Tattva and the Secret of Diksa (Part 3) 
 
Rajen Babu:Isn’t the kanistha-adhikari qualified to give initiation into the mantra? 
Srila Sarasvati Prabhupada: Where is the kanishtha-adhikari coming from? Who gave him the adhikara?A kanishtha-adhikari can never become a guru. 
Rajen Babu: Can a madhyama-adhikari give diksa? 
Prabhupada: He can only perform theinitial dutiesof diksa.It is the uttama adhikari maha-bhagavata Vaisnava who is actually the diksa-guru. There are two types of Vaisnavas – the ragatmika and the raganuga. Those who are from the eternal realm offer service to Sri Krsna directly. These ragatmikas serve Sri Varshabhanavi and Her direct expansions. Those who perform direct service to the ragatmikas and take shelter in them through the performance of smarana are raganugas. These are spiritual gurus.
(Page 15)

 If the guru becomes attached to sense gratification, loses his sense of duty, and follows a degraded path, a path other than devotional service to the Lord, he should be rejected. (Mahabharata, Udyoga Parva 179.25)
 
Sept 2 1970 letter…..
I have tried to give you all Krsna Consciousness, now it is your duty to develop it. If you remain strong on the spiritual platform then your progress will not be checked or blocked. I do not know what was resolved in New Vrindavan although Sriman Rupanuga Prabhu has informed others that he has sent a tape in this connection. I am still in darkness about the proceedings in New Vrndavana,but I have heard that Brahmananda is preaching about me that I am Krsna, that I am Supersoul, that I have withdrawn my mercy from the disciples, that I have left the Society and so on. I do not know how far they are correct, but I have written him a letter that he may not do something which may harm the interest of the Society. You are also one of the members of the GBC, so you can think over very deeply how to save the situation. It is a fact however that the great sinister movement is within our Society. I have not heard anything from Krsna das or Syamasundara., so all of you may try to save the Society from this dangerous position.
 
Madhya 24.330 purport….The mahā-bhāgavata is one who decorates his body with tilaka and whose name indicates him to be a servant of Kṛṣṇa by the word dāsa. He is also initiated by a bona fide spiritual master and is expert in worshiping the Deity, chanting mantras correctly, performing sacrifices, offering prayers to the Lord, and performing saṅkīrtana. He knows how to serve the Supreme Personality of Godhead and how to respect a Vaiṣṇava. When one has attained the topmost position of mahā-bhāgavata, he is to be accepted as a guru and worshiped exactly like Hari, the Personality of Godhead.Only such a person is eligible to occupy the post of a guru.
 
 
Some Conclusions-We can understand from the above, why Srila Bhaktisdhanta maharaja told our Prabhupada and his other GM disciples that it was OK for our Prabhupada to remain “separate” from the Gaudiya matha (GM). Seems trouble was already brewing in the Gaudiya matha. 
In these few short quotes it is very clear that a kanistha adhikari devotee can never become guru AND only a pure devotee mahabhagavat Vaisnava CAN become guru/spiritual master/acarya. But how many devotees have understood this? The answer was given above.
 
Hare Krsna
damaghosa das