The gimmick: The final frontier of cinema is...smell? So thought producer Mike Todd, Jr. who created 1960's Scent of Mystery to highlight his Smell-o-Vision technology. He equipped three theaters with conveyor belts, designed to deploy one of 30 different scents sequenced to specific triggers in the film reel.
The result: One and done. Audiences complained that the smells were hard to detect and by the time they blew through the theater, the action on screen no longer matched up. It's probably for the best — did anyone really want to experience the pungency of, say, Rocky post-fight? We'll pass.