I have written a program to automatically cleans your Gmod Directory.
It is very simple to operate and requires little to no experience with gmod and its directories. It runs with windows command via cmd.exe
Simply follow the on screen instructions and your set to go.
This program will give you the option to clear(delete) the contents of your addons folder. It will also delete the cache, downloads, downloadLists, lua_temp and gamemodes files. Additionally it will remove any misplaced folders from your addons directory.
Also, the only reason it asks for your steam name is to enable multiple users on the same computer. So dont worry, its not malicious.
Please let me know of any bugs you find.
*Make sure to run this program in the extracted folder.
Updates included in new release (11/30/09):
-Now remembers users, so no more repetitive typing.
-Now has the option for heavy or light cleaning.
-Has a tiny bit more color, lol.
-Hopefully more features on the way.
Updates included in new release (12/1/09):
-Now allows for custom gmod directories
-Remembers directory for next use
Updates included in new release (12/14/09):
-Rewrote source for improved efficiency and smaller overall size
-Cleans more thoroughly