This is weird. With CleanMyMac, I can easily scan subfolders and their sizes. If the size is, say > 3 GB, I immediately check it. Certain folders like homebrew or Android Studio cache are safe to be deleted.
I'dl like to know cases where CleanMyMac may fail.
There's now a pretty good mac clean up tool built in to macos. From the apple menu: About This Mac -> Storage -> Manage...
It breaks down the file system in various ways, one of which is developer files where you can clean build folders and caches, uninstall SDKs and a few other things
e.g. .npm, .sbt, .gradle, .cargo etc.
The compilation result of the code is often in the root directory of the project, such as maven, the sbt project will be written to the target directory, and the cargo project will be written to the build directory.
The cache files mentioned above cannot be scanned and cleaned by CleanMyMac.
Any space wasted on unnecessary things like graphics and animation that detracts from the functionality of the program is useless.