It shall be a sufficient defense to this proceeding if any defendant of record establishes any of the following:
(1) The condition or conditions described in the petition do not exist at the time of trial.
(2) The condition or conditions alleged in the petition have been caused by the wilful or grossly negligent acts of 1 or more of the petitioning tenants or members of a petitioning tenant's family or by persons on the premises with the consent of a petitioning tenant.
(3) Such condition or conditions would have been corrected, were it not for the refusal by any petitioner to allow reasonable access.