I really don't think boober is a nudist, I think he just likes his hat and scarf! I personally prefer a hat and scarf instead of the dumb clothes boys wear these days, but I think I would get beat up too much!
I think it's kind of like mice in our walls, who don't wear anything. Fraggles weren't meant to wear clothes, but at some point just started, cause there are a LOT of nekkid Fraggles in the show's background.
I've always noticed over the years that some puppets never wear or wore clothing,just their character trait I guess.Or like it was mentioned some have very little on,just one or two pieces or just accessories.