Safe automatic refactoring requires the ability to do static analysis of the code. Many refactorings are harder in loosely-typed languages.

I should have added that I am probably abusing the term refactoring if it has a precise definition. What I'm talking about is working on improving the readability of my code, but also improving its structure. Today, "spaghetti" probably doesn't refer to a tangled mess of code sequences because we've gotten rid of the GOTO, but tangled interactions between modules, many of which are vestigial.

A lot of my code interacts with hardware configurations that will cease to exist when a project is done, but I mainly look at the stuff that's potentially reusable, and making it worth re-using.

I'm using Python, and there are a lot of tools for enforcing coding styles and flagging potential errors. I try to remove all of the red and yellow before closing any program file. I don't trust myself with too much automation! "Walk before you run."

I don't think refactoring tools are that useful for refactoring, most of the time you are doing non-obvious refactoring tools can't help with anyways. Depends what we call "refactoring", tools are mostly useful for what I would call "housekeeping".

At least in the languages I work primarily in (JS and Java), I find my IDE to be pretty good at analyzing a lot of it.

Refactoring is kind of subjective, because there is rarely One Right Way to solve a problem, and you need context, so I could see why it’s not something that languages themselves take strong opinions on.