What I find interesting is that Zong Rinpoche had mentioned before that Pabongkha Rinpoche is in reality Heruka, but due to our deluded minds and our negative karma we are unable to see it as such. If what Zong Rinpoche said about Pabongkha Rinpoche is true, then all mistakes of any Buddha are not really mistakes but our own delusion and ignorance and lack of understanding because we do not understand the actions of a Buddha and therefore we impute it to be a mistake. This is a point that we have to consider if we say that high lamas make mistakes.
I would think rather, that if one Guru is enlightened from his own side, whether we see him as enlightened or not, it doesn't follow that Buddhas would be without faults. I think people generally miss the whole point in all this "Guru is a Buddha" -thingy.
From the point of view of Sutra, the Guru is not seen as a Buddha (except the Guru-Founder Shakyamuni, of course). Therefore there is no need to suppose or see either faults or purity, or to see the Teacher in any specific way.
From the point of view of Tantra, the practice is to see the Guru as a Buddha, and this must be done in a specific way. But for starters, one must understand, that it does not matter whether the Guru is or isn't a Buddha from his own side. It does not matter whether the Guru really is Heruka or not, for the practice is the same in any case. Vajramaster can be unenlightened, but if the student sees him as enlightened, the student gets the blessings just as well as if the Guru would be enlightened. And now comes the tricky part: If one has a pure mind, on the level of samadhi or dhyana perhaps, one could see and relate to the Guru on the level of enjoyment body, sambhogakaya, the pure body, and then, one would see only purity. (Perhaps Zong Rinpoche could see Je Pabongkhapa as Heruka directly.) But for most practitioners, this is impossible, and they see only the form body or emanation body, nirmanakaya, and have to relate to the Guru on that impure level. This means that one will see faults. There is no need to find faults, as the faults are a given. And it is here where the "magic of Tantra" happens.
Basic idea of practicing Tantra is that one sees and approaches a faulty thing, a samsaric thing, an impure thing, but views it as pure, as blissfull, for in Tantra, there is no dualism of pure and impure! The whole world, or mandala, is just a big and horrible charnel ground, and that is called the pure land of Vajrayogini. In tsog, one partakes of bala and madana, and considers them to be pure bliss. Also, one cannot see one's own enlightened nature if one cannot see it first in some other faulty being, the Guru. This means that if one categorically refuses to see faults in the Guru, one cannot see purity in the impure either, cannot see enlightenment within the darkness, nirvana in the samsara, or even the possibility of nirvana amidst the samsara - and therefore one is not practicing Tantra at all. If one separates the pure from impure, one has created a gap that makes Tantra impossibility. The whole point in having a Guru is that one can see one's own capability of being a Buddha right here right now, just as one is, faults and all. Those who dogmatically refuse to see enlightenment within faults, have pushed or lifted Buddha's nirmanakaya back to the level of sambhogakaya, and can not therefore see either one - those people merely have a human teacher onto whom they have sticked a label "buddha". If one says that "the Guru is totally pure", then that Guru is not an emanation body of a Buddha, for emanations exist only on the level of Desire Realm, which is by default impure. Since the Buddhas care to send emanations to help us, then I think it would be at least courteous to relate to them as such, and not to try to throw them back to a level where we cannot relate to them at all.
In short: From the point of view of Tantra, one needs to see both impurity and purity, and learn to lose the duality.
PS: I find it most inspiring when the classical Suttas and the Vajrayana agree on something. So wonderful.
