There should be a way to do that.
I know in SQL I'd use something like:
WHERE ( ( (Anime NOT IN (hated_anime1, hated_anime2)) AND (Artist NOT IN (hated_artist1, hated_artist2)) ) OR (Category=Parody) )
If I can come up with that off the top of my head, it might be possible, but it depends on how complicated the rest of the query is and the structure of the database. Obviously, if it would require a database redesign to implement efficiently, it may not happen all that soon.
Even though I can't afford to donate at this point (just spent 2 months out of work), please count me as someone who'd love to see this worked into the suggestions if possible...