This is also how I have traditionally looked at new codebases. I don't necessarily actually clean it up (I dislike changing someones style unless it is completely necessary) but I build up a mental model similar to what you're outlining. It's been really interesting with these LLM coding tools. I may not disagree with the implementation in terms of logic (it just does what I've prompted it to do after all) but something about it will 'stink'. Amusingly this feeling is the true 'vibe' of 'vibe coding' to me.

I sometimes wonder if this is the result of experience/education (I'm not a compsci major) or if it's just a naturally different way to think about systems.