Really that should be TAILS_terms=(word('tails') and word('linux' or ' USB ' or ...

Really that should be

  TAILS_terms=(word('tails')
               and word('linux' or ' USB ' or ' CD'
                        or 'secure desktop' or ' IRC '
                        or 'truecrypt' or ' tor '))
           or word('Amnesiac Incognito Live System');

because (1) you need to disambiguate the common word 'tails' but surely not the specific name 'Amnesiac Incognito Live System', and (2) you don't want to miss [tails CDROM].

See how important code review is?