Defied: Eva refuses to let the credits roll until she's verified whether or not Marcy's actually dead.
Deconstructed: The trick has been pulled so many times, No one believes Marcy dead at all and thus the show becomes boring and repetitive for the fans.
Played for Laughs: Marcy is badly beaten, and is thought to be dead. She uses this opportunity to go and scare (or "post-fatally" seduce) everybody she knows.
Played For Drama: Eva seemingly kills Marcy. The rest of the cast is incredibly distraught and they spend the next few episodes trying to cope with Marcy's death. Just when the cast abandons hope, Marcy appears and reveals that she actually survived.