A tale from Jesse Lasky Jr.

In 1927, producer Jesse Lasky who was making a film about Teddy Roosevelt's "Rough Riders" outfit of the Spanish-American War conducted a nation-wide search for a TR look-alike to take on the role of the hero of San Juan Hill. Lasky's net trawled up a man named Frank Hopper. But when production of the film started, it became too apparent that the mild-mannered Hopper was not up to re-enacting the "bully" Roosevelt. Well, there was no turning back after all the publicity surrounding the casting of Hopper. So, what to do? In his book "Whatever Happened to Hollywood?", Lasky's son, screenwriter and novelist, Jesse Lasky Jr. tells the story:

"At that moment the door was opened by a slender graying man of distinguished bearing: Will Hays, former postmaster general in President Harding's cabinet, now embarking in the 100,000 a year post of custodian of motion picture morals (to improve the national image after a few too many scandals had begun to hurt business).
"Can I come in, Jesse?"
"Glad to see you general. We have a large problem."
Hays listened, a spark showing through his glinting eyes. He looked like Uncle Sam minus the beard. When the dilemma had been aired, he spoke.
"This may been out of the far end of the diamond, Jess, but there's a simple fundamental that might apply. so basic people forget it. A man reacts the way the world treats him. Other people are his mirror, he becomes what he sees in the way they look at him. Try it out on him. Get Hopper in here, now! Instead of letting him see how worried you are, introduce him to me with the greatest respect. I'll act as though I'm meeting Roosevelt himself."
. . .
When Hopper arrived, Hays proved at once he knew how to play the required scene. He had learned how with real presidents in his Washington days. when the would-be Roosevelt came cowering into the office, eyes darting nervously around, my father began with near reverence, "General, I have the honor of presenting Theodore Roosevelt."
"proud to make your acquaintance, sir." hays responded with a formal bow. "May, I say. sir. the resemblance is perfect? But more than merely physical. I can see you have the same fearless nature, the same character and patriotism. You are the kind of man who would meet the challenge of the war with the words, 'Let us pray with our bodies for our souls' desire.'" Then he turned to my father. "Mr. Lasky, as former postmaster general of the United States, I count this as a proud moment, and I thank you for the honor of meeting this man."
Astonished at first, the new treatment hit Hopper like a bolt form the blue. Red, white and blue. As he left the office and everyone rose, it could be noted that his posture had undergone a subtle
change. His head was more erect, his step had acquired the slightest suggestion of a strut.
Orders were relayed throughout every department of the studio: The movie Roosevelt was to be treated as though he were the real T. R. As told in my father's biography, by Don Weldon, I Blow My Own Horn, this was one of the rare occasions where grips, juicers, cameramen, assistant directors - everyone, in fact, but the star - was performing to the hilt.
Unfortunately, the wormed turned too far. Under this ego-massage, the simple smalltown storekeeper became almost unmanageable. The man was submerged by the megalomaniac monster demanding total attention, obsequious respect, demanding that every scene should receive his signature of approval before he would film it.

page 60-61 of Whatever Happened to Hollywood? by Jesse Lasky Jr.