> It's kind of useless if it can't be defined

That's just the programmer/logician in you screaming "unknown feeling!" :)

Programming (for me at least) is as much of a creative endeavor as it's one of logic. You can train yourself to at least recognize "good" from "bad", even though it's much harder to teach yourself how to go from "blank" to "good", or even being able to actually define why something is better than another thing. Sometimes it's literally just "vibes" and that's OK.

If you're unable to train this feeling in yourself, maybe the best course of action is to find someone you can tell is able to better use that particular skill, and ask for their feedback.

Also studies. In art, especially painting and music, you do a lot of studies of masters’ works, to discern how they’ve decided to make their intention manifests.

Same can happen with code. People may talk about readability, maintainability,… And it can be hard to improve in those aspects. So you read a lot of code that is lauded as good, figure how people goes from ideas to a written version of it, contrast it to your approach, a d reflect upon that.