I think the more the actor lets you know what he thinks of the character, the less the audience cares - like a comedian who laughs at his own jokes.
“King Arthur was one of my heroes - I played with a trash can lid for a knightly shield and my uncle's cane for the sword Excalibur.”
“As an actor we're just like workers in a factory, we provide our services to directors. But I must do my job perfectly, and I love what I do.”