GUIDClean does not verify that the GUID strings it finds in MS Office documents do in fact conform to the published specification. It does not attempt to decode the information packed into the GUID string. (See references for a program that does.)
GUIDClean will allow you to replace existing GUIDs with any string of your choice. No verification is performed. The only requirements are that the replacement string must be of the same length and that only the HEX digit characters may be used (0-9, a-f). Likewise, the randomly generated GUIDs are bogus, and may happen to represent valid data only by pure chance.
