Cheating is a reaction when something happens, you think thats not right its against the rules.
Thus,
1. AI towns can run at well below 80%PO and not rebel.
2. AI crusades can park outside your city for several turns without deserting awaiting you to complete the crusade so they can attack you.
3. Inquisiors always burn you generals whatever their piety, while the excomed pagan worshipping opposite gets left alone to enjoy drunken romps with little boys.
4. merchants, assasins spies etc never seem to be as successful as the AI when they have similar qualities.

If they AI can screw you then theres nothing wrong in returning the compliment. However thats different to modding the structure to balance out what you percieve to be imperfections.