Every audit will follow a plan. If there is no plan, that’s evidence of negligence. The plan will show whether or not the auditor did his/her job properly. Of course if the “auditee” posts sudden enormous losses, that is evidence that there was a major problem in the auditee. Why did the audit not pick up those losses?
A profitable area for examination would the valuations of assets furnished to the auditee. Those valuations may have been provided by “independent” agents (auctioneers), commissioned either by the auditee or a third party. If those valuations were radically wrong that is a basis for litigation against the valuer to recover the loss arising from the deal or property which was the subject of the negligent valuation.
However, an auditor is obliged to take account of the possibility of fraud. Just because a valuation is on a file from an “independent” agent the auditor is not relieved of his/her obligation to consider whether the accounts show a true and fair view of the fiinances of the entity being audited. The fraud may be in the valuations.