Perhaps the only Warner Bros. cartoons not worthy of the name were the Road Runner cartoons produced by Format Films (acting as subcontactor for DePatie-Freleng Enterprises) under the mis-direction of Rudy Larriva. (They were bracketed by two far better cartoons actually produced at DePatie-Freleng with Bob McKimson directing.)
As his April Fool's joke, animation scholar Thad Komorowski has given us a pretty good overview of why Larriva's work is so rank. Sure, Larriva had at least one of Chuck Jones' animators aboard (Bob Bransford), but the other artists - which at times included even the great Virgil Ross - couldn't make a silk purse out of a coyote's ear. To borrow from my WB filmography, "Watch these cartoons and you'll know that WB censored the wrong 11 films!"
6 minutes ago