Srila Prabhupada clears up the confusion about who is a bona fide, fully empowered real guru in a lecture on the Srimad-Bhagavatam 5.6.8 in Vrndavana India on November 30, 1976
So just like ordinary cloud is made possible by evaporating water from the sea, similarly, Krsna has the sea of mercy, karunayamaya, karuna-sagara. Krsna’s another name is Karuna-sagara. So as the air evaporate or the heat evaporate from the sea, and the cloud is formed in the sky, similarly, one who has connection or the power to evaporate the mercy sea of Krsna, he can extinguish the samsara davanala. And that is guru. Guru is the cloud or he is the agent of drying water from the ocean of mercy of Krsna and turn it into a mercy cloud and pour water on the samsara davanala, and then it is extinguished. Samsara davanala-lidha-loka-tranaya karunya-ghanaghanatvam, praptasya kalyana.
Therefore guru must be authorized person, not that bhumi-phala-guru(?). No. “I am guru,” no. You cannot become guru unless you are agent to draw out the mercy water from the ocean of mercy of Krsna. That is guru. And therefore a guru is not an ordinary person.…You cannot get Krsna by studying Vedas. That is not possible. There is Krsna in the Vedas, but you cannot pick up. It is not possible. But if you go to the Krsna’s favorite person… Kintu prabhor yah priya eva tasya. Krsna’s very dear servant, confidential servant, is guru. Nobody can become guru unless he is in confidence of Krsna….We have to see whether a person is actually bona fide agent of Krsna. Then we accept him as guru. Otherwise useless waste of time. Gurur apy avaliptasya karyakaryam ajanatah. Guru is very confidential serv… Saksad-dharitvena samasta-sastrair uktas tatha bhavyata eva sadbhih. Guru is saksad hari; there is no distinction between guru and Krsna…. Whether you are actually in terms of the sastra? Whether actually you are dear to Krsna, you are most confidential servant? That we have to test… So if this confidential knowledge, one who preaches without any compromise, he is the confidential servant of Krsna. There is no compromise. This is real religion. The Krsna says, na ca tasmad manusyesu kascid me priya-krttamah. So this is the person who has received the authority to draw mercy water from the ocean of mercy of Krsna. Saksad-dharitvena samasta-sastraih.