I suggest in the cleaner there were little descriptions that pop up in a tooltip when you click an option. This way everyone that uses CCleaner can know what it is they are cleaning/removing from their computer. For example I had to google DNS Cache to find out what that was. I found that it was cache storing corresponding domain names and their IPs; With it your computer doesn't need to find the IP for google.com every time you request their home page for example. A little description for every option would make it easier for me to decide what things to clean; Right now I just select options that don't look too harmful. However, you'd need to make the descriptions as clear as possible to the average person (but not over simplified).
