Is is within the 50 stanzas of devotion to the Guru and I quote:
Verse 6;
In order for the words of honor of neither the Guru nor the disciple to degenerate, there must be a mutual examination beforehand (to determine if each can) brave a Guru-disciple relationship.
At tantric empowerments many sets of vows are taken never to abandon the practices and procedures essential for spiritual progress. The disciple pledges his word of honor never to transgress these vows, such as always to visualize his Guru as inseparable from the meditational deity into whose practice he has just been initiated. Such deities, as well as the Gurus, share the same Enlightened nature as all the Buddhas, differing only in the physical aspect they manifest.
The Guru, too, has previously pledged his word of honor never to disclose the tantric secrets to those who are unable to understand and keep them. Just as the milk of a lion should not be kept in a clay pot, so the profound and powerful methods of the tantra should not be entrusted to those who are not ready. If, having taken such vows, either the Guru or disciple should allow his word of honor to degenerate, it will be impossible for either to attain any of his goals and very serious unfortunate consequences will follow for both. Therefore it is extremely important for there to be a mutual examination between the Guru and disciple before they enter a formal relationship.
In ancient times in order to receive an empowerment a potential disciple would have to ask over a period of three years. An initiation was not at all something casual. By making the disciple wait so long, a Guru impressed on him the seriousness of entering the tantric path, tested his commitment and ensured that he was properly prepared. Often a Guru would make a disciple wait even longer before agreeing to teach him anything. He would repeatedly test his character and only when he had understood him well would he accept him as his disciple.
The disciple also must test his potential Guru and determine if he is fully qualified. He must be confident that he will be able to devote himself fully to this Master. Before entering a formal Guru-disciple relationship, you have complete freedom of choice. But once such a bond has been established, these teachings on Guru-devotion must be followed with total commitment.
Verse 7
A disciple with sense should not accept as his Guru someone who lacks compassion or who is angersome, vicious or arrogant, possessive, undisciplined or boasts of his knowledge.
Verse 8
(A Guru should be) stable (in his actions), cultivated (in his speech), wise, patient and honest. He should neither conceal his short-comings not pretend to possess qualities he lacks. He should be an expert in the meanings (of the tantra) and in its ritual procedures (of medicine and turning back obstacles). Also he should have loving compassion and a complete knowledge of the scriptures.
Verse 9
He should have full expertise in both ten fields, skill in the drawing of mandalas, full knowledge of how to explain the tantra, supreme pure faith and his senses fully under control.
In general a Mahayana Guru should have the following ten qualities: (1) discipline as a result of his mastery of the training in the higher discipline of moral self-control, (2) mental quiescence from his training in higher concentration, (3) pacification of all delusions and obstacles form his training in higher wisdom, (4) more knowledge than his disciple in the subject to be taught, (5) enthusiastic perseverance and joy in teaching, (6) a treasure of scriptural knowledge, (7) insight into and an understanding of Voidness, (8 ) skill in presenting the teachings, (9) great compassion and (10) no reluctance to teach and work for his disciples regardless of their level of intelligence.
A Tantric Master must have even more good qualities, as listed in the text. Most important is that he be an extremely stable person, with his body, speech and mind totally under control.
There are two set of ten fields in which the Guru must be a complete master. The ten inner ones are essential for teaching the yoga and anuttarayoga classes of tantra, which stress the importance of purifying mainly internal mental activities. These are expertise in (1) visualizing wheels of protection and eliminating obstacles, (2) preparing and consecrating protection knots and amulets to be worn around the neck, (3) conferring the vase and secret empowerments, planting the seeds for attaining a Buddha’s Form Bodies, (4) conferring the wisdom and word empowerments, planting the seeds for attaining a Buddha’s Wisdom Bodies, (5) separating
the enemies for Dharma from their own protectors, (6) making offerings, such as sculptured tormas, (7) reciting mantras, both verbally and mentally, that is visualizing them revolving around his heart, (8 ) performing wrathful ritual procedures for forcefully catching the attention of the meditational deities and protectors, (9) consecrating images and statues and (10) making mandala offerings, performing the meditational practices (sadhana) and taking self-initiations.
The ten external qualities are required for teaching the kriya and carya classes of tantra, which stress the importance of purifying mainly external activities in connection with internal mental processes. These are expertise in (1) drawing, constructing and visualizing the mandala abodes of the meditational deities, (2) maintaining the different states of single-minded concentration (samadhi), (3) executing the hand gestures (mudras), (4) performing the ritual dances, (5) sitting in the full meditational position, (6) reciting what is appropriate to these two classes of tantra, (7) making fire offerings, (8 ) making the various other offerings, (9) performing the rituals of (a) pacification of disputes, famine and disease, (b) increase of life span, knowledge and wealth, (c) power to influence others and (d) wrathful elimination of demonic forces and interferences, and (10) invoking meditational deities and dissolving them back into their appropriate places.
It is not sufficient for a Tantric Master merely to know how to perform the superficial actions of these above rituals. He must actually be able to do them. For instance, when consecrating an image of a meditational deity, he must be able to invoke the actual deity and place it in the image, not merely recite the words of the accompanying text. If you take as your Guru a Master with all these qualifications and powers, and he accepts you as his disciple, you must devote yourself fully to him. Although it is possible that out of delusion you might disagree with your Guru, never show him disrespect or despise him from the depth of your heart.
Verses, 7, 8 and 9 clearly states the quality that the disciple needs to check if the Guru has. If the potential disciple cannot see these quality it doesn't mean the potential Guru don't have it. If the disciple do not understand why the Guru needs these quality then then the disciple really need to study to find out why.
Clearly, both the Guru and the disciple must check each other out if the relationship is beneficial to the disciple.
It is because the disciple has not understood the reasons and the consequences of it that these issues of boundaries arise. It is a sign that the author do not understand Guru Devotion.
Verse 24
(A disciple) having great sense should obey the words of his Guru joyfully and with enthusiasm. If you lack the knowledge or ability (to do what he says), explain in (polite) words why you cannot (comply).
This does not mean that you should become a mindless slave or that your Guru can take undue advantage of you. As you are aiming for the complete freedom of Enlightenment, there must also be freedom in the means of attaining it. You should never follow your Guru’s wishes simply because you feel obligated or forced to obey.Rather try to understand his intentions and aim. Your Guru will only tell you to do what is beneficial for yourself and others. What he asks may be difficult and its immediate purpose may not be obvious, but you should receive his advice joyfully and with deep gratitude for his concern with your welfare.
Examine yourself honestly to see if you can follow his wishes. If there is no way in which you can comply, do not be rude or arrogant. Explain politely and with extreme humility what the difficulty is. Your Guru will not be unreasonable; as a Buddha he is filled with great compassion.
If, however, you can avoid transgressing his advice, this is best. Following the spiritual path as he directs, you can attain not only the ordinary powerful attainments (siddhi) of extra-physical and mental powers common to non-Buddhists, but depending on your motivation, a higher rebirth, the happiness of Liberation or the supreme powerful attainment of Buddhahood.
Verse 48
After a disciple has taken refuge in the Triple Gem and developed a pure (Enlightened motive), he should be given this (text) to take to his heart (how to abandon his own arrogant self-will and) follow in his Guru’s footsteps (along the Graded Path to Enlightenment).
Verse 48 clearly states that Guru Devotion is practice in order to abandon the disciple's own arrogant self-will and follow the teacher along the path to Enlightenment.
My personal experience is that the Guru only want us to have one basic quality. That is sincerity. Be honest and do as we promised. If we cannot comply, then we need to be sincere and be honest to the Guru. He will have his methods. If we are truly sincere, the Guru will be patient. We will succeed.