Corruption is the sign and behaviour of lacking and/or losing judgement and wisdom.
Inability to tell what is right and what is wrong can be due to lack of judgement and wisdom. In normal situation, it may still be fine. However, it will never be okay when one intentionally unable to tell what is right and wrong. That is corruption.
Like many things else, there are degrees of corruption, how a person okays a corruption, either for self or for others, is their negative contributions to group or the system. This negative poisonous characteristic come from corruption will always erodes wherever it is happening.
More in the book!