The Hair
In "The Great TV Sitcom Book" by Rick Mitz, (1980, Richard Marek Publishers), it says of his show:
"In the first episode of 'The Many Loves of Dobie Gillis' in 1959, the color of Dwayne Hickman's hair changed from light brown, (at the beginning of the show), to blond by the end show's end. Throughout the years-and the show ran for four of them- his crew cut grew out and the color would eventually change back to brown."
I've been watching a collection of 36 selected episodes on DVD from Nostalgia Family Video and I noticed this, too. Obviously, the dark brown he wears for the series' last three seasons is Hickman's natural hair color and they decided his hair color didn't matter. Hickman is a very handsome man. The question is: in which hair color does he look better- or maybe the word is most "distinctive". I like the blonde Dobie of the first year better than the dark brown Dobie of the subsequent seasons but think the light brown look of the premiere, (which was presumably also the pilot), is the most striking look. He really does look like a bronzed statue of young American manhood.
But maybe that's why they let him change to his natural hair color. Perhaps he looks too good at the beginning and no one would believe that he has trouble getting girls. The Dobie of the last three seasons is more "average" looking and maybe that's what he needs to be.