RADB based filters

Hi all,
  I was wondering what those of you who are doing RADB/MCI-RR/ANS RA
filtering were doing about large networks which do not register their
networks in the RADB. It would seem unwise to simply trust their
announcements, and even more unwise to simply ignore their announcements,
so... Whats the common parctice in this scenario?

Inverse filter what you know you don't want to hear from them.