A professionally executed Inventory is an accurate detailed document that will include a schedule of condition of the property itself as well as the fixtures, fittings and contents at the beginning of a tenancy. It is compiled to protect both the landlord and the tenant at the end of the tenancy from any unwarranted disputes.
If there is an insufficient, outdated or, even worse, no Inventory, then there will be no evidence of the condition of the property at the start of the tenancy. This means that there is no documented proof of damage or misuse.
If there is a clear indication of the condition of the property at the start of the tenancy then this can be used as a measure against the condition of the property at the end, with allowance for fair wear and tear.