A tenant is leaving the property he had rented at the end of the contract period. The landlord has arranged for prospective future tenants to view the property, while the current tenant is still there.
The current tenant is aware of various issues / problems with the property and/or the behavior of the landlord.
What, if anything, may or should the current tenant say to prospective tenants?
Does it make a difference whether the current tenant is volunteering the information, as opposed to answering questions that the prospective tenant has asked?
Possible angles to explore could include the prohibition against standing by when another is at risk of harm versus the prohibition against slander.
If it makes a difference, assume all parties are observant Jews.