Concerns about corruption depend on actual instances of corruption, which the Fourth Turning encourages by its nature. (Although people won't really be concerned about it until the First Turning starts - too much else going on.)

 

Credit Mobilier (1872) is one of the main inspirations for this idea of corruption found during First Turnings that started in the Fourth.

https://en.wikipedia.org/wiki/Crédit_Mobilier_scandal

As are the Valachi hearings (1963)

https://en.wikipedia.org/wiki/Valachi_hearings

At some level, the McCarthy hearings, along with other investigations into Communist influences, can be seen as concerns about corruption as well.

https://en.wikipedia.org/wiki/Army–McCarthy_hearings

Can't really talk about Corruption without mentioning the Bloodguard, for whom the Vow was everything, and anything that was not the Vow was Corruption. 

https://unbeliever.fandom.com/wiki/Bloodguard