You can't really define what "corruption" is under a dictatorship. It's like trying to define "officer misconduct" in a torture prison. There is no rule of law, and even if there were, it is "legal" for the dictatorship to plunder public wealth and use it for personal gain.
For this reason & more, you can't believe dictators when they say they're fighting corruption. When they declare an "anti-corruption campaign", it's about consolidating power by going after rivals, or about PR (or both).
People who believe that dictators fight corruption are either morons, or are complicit in the corruption or its cover up. Dictators fighting corruption? Corruption is the business model of dictatorship.