U r absolutely wrong.. The ball joints allow the front wheels of car to move up and down to soak up road bumps and to pivot for steering...If ball joints are worn out, they dont produce sound on a smooth road.. But if the car goes on any bump, they will produce GHUD GHUD sound, you ll hear clunking sounds from the front as the joint rattles in the socket cuz they become loose..
See the pic for reference..