Tell me, bhaktajan, are Vaishnavas, or other Hindus, the only ones who are able to correctly discern "real Gurus?"
A] "other Hindus" may very well refer to the Common layman Hindu on the street of India ---in which case it should be expected that a native born person knows the ways of provincial traditions as they are in the "old country".
Just as any Tourist can gain gidence by the locals living in the district being traversed by the tourist.
B] I as a Card carrying Hare Krishna Devotee (as we casually refer to ourselves) begin with a copy of the Bhagavad-gita that was translated by Swami with authentic bone fides.
Swami Bhakti-vedanta translated the Gita into English and attached his own commentary --[as is traditional protocol for authentic old-school Swami and Sanskrit Pandits]--- the provocative & scholarly editorial gibe that the swami did was to publish the classical Bhgavad-ita with the emphatically stressing the issue of PROVINANCE, the swami did this by Titling the Gita as such:
"The Bhagavd-Gita As-It-Is".
This is the start of Swami Bhaktivedanta's "Back-to-basics" approach to revealing authentic and authorised representation of Hindu Vedic Literatures that set the standard at its highest for and johnny-come-lately Yogi-group-leader.
Then next comes the authentic Swamis of India that happen to be of the school of thought of Vedic Mysticism that proponds [as per their sect] that there is no Godhead ---they are referred to as "Sunya vadi" or "Maya vadi".
Sunya (zero, zed) & maya (shakti-prakriti) are all that exists and thus a state of Nirvana (lit. 'without qualities') is the DEFINITION OF LIBERATION/SALVATION/MOKSHA.
So the only problem for us souls in samsara, was accessing the truth of the revelations of the Vedas ---for most of us transmigrating souls since time-immemorial--- we all have had to wait countless births of fruitive behavior learning by the carrot or the stick ---until a Bonefide Guru presents the most complete nuanced translations of those Vedas.
As a result of learning the complete story of the Veda's contents ---it becomes imperative that WHATEVER IS REALLY SAID IN THE VEDAS should be transmitted to the yoga student and the world public without any diminuation or watering-down of the contents.
So Yes, the first thing a HK devotee must learn from the Vedas is Waht is the Vedas? and What does the Vedas Say?
The Spiritual contents and message of the Vedas have been hidden for many moons ---and it did get revealed during the cultural revolutions of the 1960's ---that is why the Beatles left India, but George Harrison stayed on to study Krishna Consciousness and Chant The Maha-mantra.
Krishna Consciousness is NOT a New-wave new-age Slogan ---Krishna Consciousness is the essence of the Veda's revelation.
Bogus Gurus were all in vogue when bhaktivedanta Swami came to the west to propagate this revelation in the Vedas.
Krishna Consciousness means being aware of Krishna ---because Krishna is the Godhead that is Yaweh & Allah.
The name fame form personality paraphenalia and pastimes of Krishna are the complete and final revelation of the Vedas.
You can take it ...or... if you leave it, you are free to continue to wander in samsara.