gimmick

a drawback or difficulty that is not readily evident; "it sounds good but what's the catch?"

something unspecified whose name is either forgotten or not known; "she eased the ball-shaped doodad back into its socket"; "there may be some great new gizmo around the corner that you will want to use"

any clever maneuver; "he would stoop to any device to win a point"; "it was a great sales gimmick"; "a cheap promotions gimmick for greedy businessmen"