The Holy Prophet of Islam (peace be upon him and his progeny) said:
إذا رَأَيْتُمُ الرَّجُلَ لايُبالِى مَا قالَ أَوْ ما قِيْلَ فِيْهِ فَإنَّهُ لَبَغيَّةٌ أَوْ شَيْطانٌ
When you find that a person is indifferent to what he says or what is said about him, you shall know that he is either unchaste or devilish.1
Drowning in various sins makes man indifferent to any and every accusation. He does not care about what he says about others and what is said about himself. Such persons are mean, shameless , devilish.