I recently heard a sermon ( I forget the speaker- either Keller, Allen, or Tullian T.) and there was a quote from Martin Luther about "thanking satan for pointing out my sin because it reminds me of the gospel - Jesus died for sinners".

this blog below has some similar quotes.
http://kerdos.wordpress.com/2011/05/26/preaching-the-gospel-to-satan/

Therefore, Satan, you will not prevail against me as you try to frighten me by showing me the magnitude of my sins and to plunge me into anguish, loss of faith, despair, hatred, contempt of God, and blasphemy.  In fact, when you say that I am a sinner, you provide me with armor and weapons against yourself, so that I may slit your throat with your own sword and trample you underfoot. You yourself are preaching the glory of God to me; for you are reminding me, a miserable and condemned sinner, of the fatherly love of God, who ‘so loved the world that He gave His only Son, etc.’ (John 3:16). You are reminding me of the blessing of Christ my Redeemer. On His shoulders, not mine, lie all my sins. For ‘the Lord has laid on Him the iniquity of us all,’ and ‘for the transgressions of His people He was stricken’ (Is 53:6, 8). Therefore when you say that I am a sinner, you do not frighten me; but you bring me immense consolation.”
Martin Luther, Works, vol 26, p36-37.

That truth of Luther's is SO IMPORTANT for our lives. when we really believe the gospel then we can admit our sin. I know the doctrine of this, but not the practice in my life. I'm so prone to being defensive or trying to justify my foolish sinful anger or petulance.I tend to live by the motto "I don't mind you calling me a sinner as long as you don't treat me like one." It's OK to admit in some real way that I'm a sinner, but don't actually point out real sin, embarrassing sin. Let's keep it all theoretical.
But as Luther said somewhere, "We have a real Savior for real sinners, for such we are".
To deny & justify/rationalize my sin, or defend myself is to deny the Gospel - Jesus came to save Sinners.