The first season was (relatively) serious. It only devolved into pure camp in the 2nd & 3rd seasons.
(Trivia: the guy losing his dignity in the carrot suit is actor Stanley Adams, who also portrayed conman Cyrano Jones on the Star Trek episode "The Trouble With Tribbles")
That was the episode where they had to order Guy and June off the set since the actor/actress could not stop laughing.
And yes, in the first episodes Dr. Smith was an evil genius -- VERY dark and not funny at all. The Robot followed his orders without question (the Robot is why they got lost to begin with).