it's all in the way it's presented, really all the information is available anyway, but compare TC's writing or Berardi's to something from pubmed. Making it acceptable to your audience is the goal
I lecture in the uk, and try and work in lots of jokes and interactive elements, use examples from the audiences comfort zone etc. watch your favourite comediens/tv presenters, look at the timing..build up...wait ...deliver
for any would be trainer, you have to look the part or who will believe in you
also having something unique has to be the answer. What do the T guys you mention have that others do not?