After the fight with the boss, in the Mystery of King Crimson arc,
Bucellati “dies”, and when Giorno arrives, his soul was leaving his body. Giorno healed his body and he resurrected, I think. After that, it is shown that his wounds don't show many, if not none at all, signs of blood or other types of harm.
In the Green Day and Oasis story arc, Green Day don't have any effect in Buccellati because
the mold doesn't spread to dead things, meaning that Buccellati body was dead but he still is alive.
Well, for this question to be answered, I need to know what the hell happened at the San Giorgio Maggiore church and how can Gold Experience resurrect someone.