I haven't seen this show since it originally aired, so I'd have to say my comments are about as pure as you can get, without the bias of time. Yeah, I'm sure if I saw it now on Nick or someplace, I'd probably cringe (that's what happened when I saw Man from Atlantis again after all these years, a "great" show that now I see was pretty cheesy). Still, the true test of a TV show is whether the viewer likes it, and remembers it, and brudduh, lemme tell ya, in the '70s I remember thinking this show was simply the hippest cartoon on the box. Anyone remember the Wonder Bread trading cards? There were 16 cards in the set (each spotlighting a Saturday morning show), and you'd get one in every new loaf you bought (they did it again later when Star Wars came out, and I collected those, too). One of those cards was a Butch & Sundance Kids card, and as silly as it sounds, it was a treasured item. I never once mentally compared the show to Scooby Doo, and considering that concept now, Scooby'd lose the fight. Butch & Co. weren't copies of it, they, and all shows like it, were simply fitting into a popular mold of the time.
So yeah, it may be a goofy, cheesy cartoon, but it was a lot of fun, and I'll always remember it fondly.