I observe it a lot in people. A person complains about something they feel is intolerable in someone else and they can not believe “the stupidity” of the other person. Then, in a short time while the compliant is fresh in my mind I observe the same person who made the complaint do the same thing they have complained about.
It is the dangers of pride that make us fail to see our own faults. We can easily find faults in others, but never can see our own faults. This hinders our chances of repentance.
Then I take a look at the fact that while I am noticing so many of these cases, I have not taken time to see my own faults. It seems that the faults we see in others are often within ourselves.