Opera Internet Cache:
When analyzing it say (example) 1014 files found.
After cleaning it reports (about) only half of the files is removed.
Same is with the size.
Manually checking shows CCleaner is reporting the files (size) found roughly double of what really is there.
CCleaner does not scan/cleanup the cached icons in Opera which are in:
C:\Documents and Settings\<username>\Local Settings\Application Data\Opera\Opera\icons\
This is on XP SP3. Could be another folder on another OS.