desperately wicked

"The heart is deceitful above all things, and desperately wicked: who can know it?" 

~Jeremiah 17:9 (KJV)

"We can form our opinions of that which we know not, only by placing it in comparison with something that we know. Whoever therefore is over-run with suspicion, and detects artifice and stratagem in every proposal, must either have learned by experience and observation the wickedness of mankind, and been taught to avoid fraud by having often suffered or seen treachery; or he must derive his judgement from the consciousness of his own disposition, and impute to others the same inclinations which he feels predominant in himself." ~Samuel Johnson