From the introduction:
This book details many new evil Quabals and orders. Some of them are aligned with the Red Death, some of them fight it, others are ignorant of it — all are unsuitable for anything besides NPCs.
Playing evil characters goes against the grain with everything that Ravenloft stands for. Gothic Horror plays against people’s compassion, and in my experience, allowing someone to play a character from an evil society tends to dull, or belittle the horror. Many of the Quabalists in this book are tortured souls who have sacrificed much for vengeance, love or hatred and few can still be considered human.