I heard this when I was a kid. When I called my sister a "pig" she would abruptly inform me: "It takes one to know one."
We all know and say that all sin is evil in God's eyes and no sin is better or worse than other sins. Still, some sins bother us more than others. A preacher can snap and in anger insult his ministry staff. Later he apologizes and is forgiven. But if that same preacher commits adultery with the deacon's college-aged daughter--he is fired. (We'll save this dicussion for another post, someday.)
Similar to pet-peeves regarding sin, there are certain kinds of character flaws I see in people that bother me more than others. When I see someone doing certain things or displaying a certain attitude it disturbs me more than other things that I might find more "forgiveable." Namely--arrogance and pride.
There is nothing I loathe more than arrogance. The problem is that I seem to run into it everywhere. Arrogance is the attitude of "I'm better than you." It is the opposite of what Paul commanded us to do in considering others better than ourselves. That would be humility. But humility seems hard to find.
I keep running into people who think they are better than me. No one considers me better than them. How arrogant of them! They should know I'm better than they are. They should treat me better! They should be praising me a lot more and seeing my value. They should ask me for my opinions instead of telling me theirs. How arrogant!
Oops. You see what I just did? I projected my own arrogance. Why do I think I recognize arrogance in other people so well? It takes one to know one. I recognize arrogance because I desire humility in others more than I desire it in myself.