Let me put ur argument another way.
janab-e-ali: Hey, they claim they are mr. clean and honest. Most of the time they are but i also saw them cheating sometimes. They are no mr. clean if u ask me!
janab-e-ali: However, I am better then them because I dont claim to be mr. clean, I am a crook and i know it. So it does not matter if i steal all the time!
I hope it is easier to understand.