This feature is already in Pages '09 (I can't speak to their downgraded '14 version), and it's *great*. You can turn non-printing characters on, and your eyes don't swim in the solid wall of black screen squiggles.
This feature is already present in LibreOffice 4.3. See https://wiki.documentfoundation.org/ReleaseNotes/4.3#Solarized_blue_for_Non-printing_characters
Please test the latest versions of any software before reporting issues ;-).
*** This bug has been marked as a duplicate of bug 68071 ***