At EB's time frame there probably was some corruption yet I doubt that seeing some were still true to Lycurgus that they would be as corrupt as some other Greeks, but Sparta at her glorytime from 700 till 450 BC would hardly know any corruption.

Sparta wasn't a dictatorship, it often fought against states with Tyrants and put an Olycharcy in play, if only to get rid of what might be a future problem.