I agree about the possibility of existence of these, the issue is that when the subject is more and more visible the ratio of quality work to self-serving work drops off precipitously. Sometimes it is not easy to tell which is which. Everybody is prone to being manipulated by good production values, and an air of informed authority to some degree.

I remember a friend watching a Tony Blair speech coming up to Iraq saying "I disagree with everything he's saying, but the language and sense of authority is strong enough that it feels like it is convincing me anyway"