I believe she was originally inspired by someone else's character, and the queer-coding was entirely accidental.
Add an audience deliberately deprived of positive representation (for decades, deliberately queer-coded characters tended to be villains or comic relief, and explicitly LGBT characters tended to come to a tragic end), and this sort of thing's bound to happen from time to time.
I can't believe that Shaggy wasn't intended to be a stoner, thobut. Scruffy, drives a van with a custom flowery paintjob and constantly hungry? They knew all about hippies in the sixties.