Rich - The cleaned designation reflects when the cleaning physically damages a coin, such as by scratching it, making the cleaning commercially unacceptable. Commercially accepted forms of cleaning, such as dipped and restored coins, where the process did not damage the surfaces, are not designated as being cleaned.

Here is information from the Pcgs website - Cleaning
Surface damage due to any form of abrasive cleaning. "Cleaned" covers a wide range or appearances, from a grossly polished coin to one where faint hairlines can be seen only at a particular angle or in only one area on an otherwise perfectly normal coin. This is perhaps the most frustrating of all the No Grades, because subtle cleaning is often difficult to detect in less-than-optimal grading conditions. "Dipping" (the removal of toning with a chemical bath) is not considered cleaning under this definition.

John