As a little kid, I always had an extremely uneasy impression of Dr. Smith, beyond being an underhanded traitor. I realized later he came across to me a a creepy child molester. I have no idea what he was like in real life, but his role just reeked of it to me.
When I was in school, we had to listen to an audio recording of Hamlet starring Harris in the title role. I can remember the “to be or not to be” soliloquy in his whiny Dr. Smith voice.