DAX: The zhian'tara is a ritual where joined Trills get a chance to actually meet their previous hosts.
KIRA: Meet them? How?
DAX: That's where you come in. If you don't mind, I'd like to borrow your bodies for a few hours.
O'BRIEN: What do you mean borrow our bodies?
DAX: If you agree to participate, the memories of one of my previous hosts will be temporarily removed from the symbiont and imprinted onto you. You essentially become one of my hosts for the duration of the ritual.
BASHIR: And how is this accomplished?
DAX: The memories are transferred telepathically by a Guardian.
I would think dying trill would be honored to do such a service to keep the symbionts purer and ethical, at least to some degree. It'd also give the ones who never got to host somebody a chance to join even if briefly with a negative host. They could set certain parameters like physical violence, murder, cruelty, rape, etc.
Wouldn't it be easy enough to transfer a negative host like Joran to a person who is on the verge of death to get rid of such a negative host who is a murderer?