I suggest to introduce a "Deep Clean" button on CCleaner form that can be used to clean files and folders that you want to clean before backup of HDD (using image tool) but not on normal CCleaner clean.
This will be a function to clean unnecessary files and cache that you normally want to ceep but may not want to a backup of. Like Google Earth cache, Google Picasa 3 small image library, Spotify temp files and others. Adding folders manually must be possible.