I think Snuffles is the dog the original poster was looking
for. He hung out with Quick Draw McGraw but was *not* his
sidekick (which was Babalouie). Occasionally Snuffles would
be enlisted to help track down criminals; but he would only
cooperate when dog biscuits were available.
On the other hand, I think Muttley, sidekick to Dick Dastardly,
looked *a lot* like Snuffles. Since both were Hanna-Barbera
productions, perhaps there's something more here than we
previously thought. Is Muttley really Snuffles "on the
dark side?" Is there a thesis here?