I do still like to clean out ~/.cache from time to time, often because of the thumbnail cache (which more or less rebuilds itself to the same size within a few days, so kind of pointless sometimes).

No need for an application, though. Just an alias (well, abbreviation in fish) when I feel it's getting too much.

It's completely pointless for anything else. This does remind me to check for empty or left over ~/.config and ~/.local/share folders, though. Haven't cleared those out in a while.