If you've never read the series of Awake! articles on propaganda referenced in my post above, you really owe it to yourself to do so.
They are very well written and clearly define what propaganda is and how many different groups and individuals have used it in the past and continue to use it today.
When you then understand that the writers of the WT publications clearly understand propaganda, can recognize it in the work of others and know how to use it, it then becomes obvious that at least some of their use of its techniques in their own writings is deliberate. (I'll acknowledge that some may also be unconscious due to their beliefs and biases).
But the key point is this: If the writers of WT publications are guilty of even one single deliberate act of using the techniques of propaganda in a dishonest way to lie, deceive or otherwise mislead, then it is prima facie proof that they are not God's representatives.
It's really that simple.