A scandal can be distinguished from a controversy. Immigration policy became controversial in the 90s, the foreshore and seabed in the 2000s. Even though there were bungles, and offensive views and policies were aired, the underlying issue was always sharp disagreement over core values and policies.
In a scandal, the underlying issue is wrong-doing.
Except when it’s a 'Kinsley gaffe', named after the first political botanist to identify this species in the wild. In these cases, the scandal occurs when a politician says something that is true but they shouldn’t have said, rather than does something wrong.