The problem with `git clean` is -X vs -x. -x (lowercase) removes EVERYTHING including .env files and other untracked files. -X (uppercase) removes only ignored files, but not untracked files.
If there is a Makefile with a clean target, usually the first thing I do when I start is make it an alias for `git clean -X`.
Usually, you want to keep your untracked files (they are usually experiments, debugging hooks, or whatever).