Myth: Linux Doesn't Need a Registry Cleaner
Some say Linux's .rpm and .deb installation packages uninstall cleanly, so there is no need for any registry cleaners like CCleaner. Here are a few counterexamples to the myth:
Years ago you installed OpenOffice.org version 1, and since you've upgraded to version 3. Now you wonder why Firefox still associates .doc files with OpenOffice.org version 1, which you long ago deleted.
OpenOffice.org didn't support .rpm or .deb installations until version 2. Version 1 copied files (including file associations and menu entries) to the user's home directory.