Yes, you can spray paint door knobs, and they will look 1000% better
All the doors in my home are seriously ugly. They are faux wood hollow doors with old scratched brass knobs.
I know, nasty. I’m slowly painting all the doors white and painting the knobs. I would just replace them but when you think about how many doors and knobs are in your house the costs add up quickly. So I turned to my old faithful friend. Paint.
Give your knobs a good scrub (wow, that just sounds wrong!) and then apply several coats of spray paint. Let dry completely and attach back to the door.