There is no person on earth so righteous, who does only good and does not sin (Ecclesiastes 7:20).
Reading the suggestions for ridding oneself of character defects, someone might say, "These are all very helpful for someone who has character defects, but I do not see anything about myself that is defective."
In the above-cited verse, Solomon states what we should all know: no one is perfect. People who cannot easily find imperfections within themselves must have a perception so grossly distorted that they may not even be aware of major defects. By analogy, if a person cannot hear anything, it is not that the whole world has become absolutely silent, but that he or she has lost all sense of hearing and may thus not be able to hear even the loudest thunder.
In his monumental work, Duties of the Heart, Rabbeinu Bachaye quotes a wise man who told his disciples, "If you do not find defects within yourself, I am afraid you have the greatest defect of all: vanity." In other words, people who see everything from an "I am great/right" perspective will of course believe that they do no wrong.
When people can see no faults in themselves, it is generally because they feel so inadequate that the awareness of any personal defects would be devastating. Ironically, vanity is a defense against low self-esteem. If we accept ourselves as fallible human beings and also have a sense of self-worth, we can become even better than we are.