I spent a part of my professional life speaking before audiences. Public Speaking is an art. Before I continue - I'm talking about talented speakers, not their prejudices, politics, religion, etc.
Paul Harvey was an excellent speaker. He knew how to deliver a story and a statement - He kept his audiences attention - and always brought them back for more. Other notable speakers include TV Evangelist Jimmy Swaggert ( Dan Rather once said of him - "One of the Best!") Ted Koppel, formerly of ABC, currently a NPR commentator. President Obama, President of the United States is a formidable speaker -
Recognizing a good speaker is easy - you understand what they have said, they kept your interest - and the meaning is without question,
It's pretty simple...Subject Matter, Delivery, confidence, simplicity.