Now, here's an interesting comparison: two nearly identical screen tests for the 1960s Batman TV series. One features the familiar team of Adam West and Burt Ward, and one is Lyle Waggoner (who would later play Steve Trevor on Wonder Woman) and Peter Deyell.
Waggoner, in many ways, is clearly a more apt choice to play Batman/Bruce Wayne. With his chiseled good looks and perfectly swept-up jet black hair he looks like he practically walked out of a Bob Kane comic book. His delivery is also far more natural and something we'd expect to see in a typical action TV show.
In contrast, West's performance is -- as far as I can tell -- unintentionally hammy. He shares with William Shatner a very strange method of reciting lines, with pregnant pauses in unusual places.
And yet -- had Waggoner been cast, the 1960s Batman TV show would have probably been more of a footnote in broadcast history than an influential phenomenon.
It was West's oddness -- and, one might say, even sincerity -- that won out.
Bonus: "...and when poor Mrs. Cooper finds out what you were really doing on those supposed fishing trips...the blow will kill her!"