Nihilistic? I might as well say, you sound as if you think there is a truly existent pureness. Yes, Shakyamuni Buddha is a pure teacher, the teachings of the Shakyamuni Buddha are pure teachings. As for the flesh and blood teachers we have with us now: there are good teachers, effective teachers, honest and ethical teachers but pure...no. There are good teachings, effective teachings, but pure... The teachings we have are mediated by teachers who are not fully enlightened, how can these then be pure?
It sounds like you are saying, indirectly, that Buddhas cannot help all living beings because they cannot appear as Spiritual Guides. How do you know that these flesh and blood teachers are not enlightened, just because they appear as ordinary? This would imply that there is a break in the lineage, because although there might be a lineage of scripture, what you're saying is that there is no lineage of realisation. I don't believe that. Even at the time of Buddha, some people saw him, a fully enlightened being, as a very limited being so their perceptions were wrong. You can't believe everything that appears to your mind. Naropa saw Tilopa as an old man who fried fish alive, Asanga saw Buddha Maitreya as a dog, etc. Even in the golden age, people got it wrong!
I'm not suggesting otherwise, however there is a big difference between having some purity and being pure. Though I work towards developing perfect uncontrived renunciation and bodhicitta, my aspirations and motivations are not pure. They are mixed with all the mundane thoughts of the eight worldly dharmas.
One of the benefits of death meditation from the lamrim is that it prevents the eight worldly concerns and makes our Dharma practice pure, therefore I would say that if we have a realisation of death, our Dharma practice will be pure.
According to the Abhisamayalamkara, the hindrance of manifest pride is separated from with the awakening of the Mahayana lineage, with the development of great compassion so this is prior to generating the mind of enlightenment, uncontrived bodhicitta. Manifest pride is having pride in qualities that one does possess... which of us can say that we honestly take no pride in our achievements and abilities? And if we do, then by this measure, we have not even awakened the Mahayana lineage.
Again, I would say that if you have love, compassion and humility through exchanging self with others, pride will not be a problem because we're doing our practice for others.
We can create pure karma without a pure motivation? Hmmm, here was me thinking that intention was important, not just the activity. So if I give a large donation of money to a hospital in order to further my political standing, I'm creating pure karma and practising perfect generosity? Are you sure that's how it works?
In general, we need a good motivation to create good karma, but due to the power of the Three Jewels, simply beholding Buddha's image is a cause of liberation, even if you look at it with an angry mind. This benefit comes because of the power and purity of the object, not from our motivation. In Heruka Tantra it is said that just by seeing a sincere Heruka practitioner we purify our negativities and attain liberation. We don't need a special motivation because we receive the blessings of Heruka abiding at the heart of that person.
In the example you gave, you're right - if our motive is selfish we do not create good karma, even if our actions looks ostensibly compassionate.
I repeat, claims of pure teachings, pure traditions, pure teachers are for me a red flag. They sit alongside claims of being racially pure as being divorced from reality and a hindrance to being a decent human being never mind a buddhist practitioner.
Okay, fair enough but I still disagree