The Tenant, upon vacating, is responsible for leaving the premises exactly as they found it. However, not all Tenants leave the place clean and free of dirt, dust and grime. Therefore it is advised that you do a spring clean prior to showing through prospective Tenants and then again before the new Tenant moves in. You want to set an example of what you expect when they vacate the premises in the future.
Prior to the new Tenant moving in, you as a Landlord are responsible for ensuring the property is well-repaired and fit for living at the start of tenancy. Residential premises must always be ‘fit to live in’.