Many cynical Romans, perhaps rightly so, suspected that the purpose of adding sweet-smelling herbs such as iris was simply to disguise the onset of acor from naive buyers. At first, the bacteria would form a near-invisible whitish film on the wine's surface and, as they multiplied, cause the wine's acidity to increase quite quickly. The wine was ruined long before the changeover to vinegar was at all obvious to anyone's sense of taste.
A suggestion of various Roman jurists, that a buyer insist on sampling a batch of wine before signing off on its purchase, really offered protection only against outright fraud, i.e., when the seller knew full well that what was in the amphorae was already vinegar through and through. Since the wine's degradation could occur silently in even an initially sound wine stock, during the jostling of its transportion, or its later storage, legal aspects of these matters often were unresolved and contentious.