In The Many Loves of Dobie Gillis, Dobie's best friend is Maynard G. Krebs, as played by Bob Denver. Maynard is a beatnik, loves jazz, and is quite out of touch with reality. I don't remember any hints or indirect references to him using drugs. In the 1960s, Hanna-Barbera created Scooby Doo, Where Are You? and the main characters were based on the four main characters of the first season of Dobie Gillis. (Freddie was based on Dobie, Shaggy on Maynard, Daphne on Thalia Menninger, and Velma on Zelda.)
Many people point out that Shaggy shows all the signs of being a heavy pot smoker (always hungry, always eating, but never gaining weight, talks to his dog all the time...), but I've never seen any hints that the character he was based on, Maynard G. Krebs, was supposed to be on drugs.
Granted, this was the 1950s, so the producers could not make direct references to drug use in a family show, but there never seemed to be even indirect references or indications of drug us.
Was there ever any indication Maynard used drugs? Were there ever comments from producers or writers or actors that it was assumed but not shown?