My INTJ best-friend tells me that my worst fault is the tendency to see all my faults as loveable. He'll tell me I'm too manipulative and I'll hear "You really get people." He'll tut-tut-tut me for being irresponsible and I'll read into it "you're a free spirit."
And since I've got the traditional ENFP circle of many great friends who love me despite my flaws, I tend to think "How bad could my faults REALLY be?"
This whole thought process is, I know, a pretty damning fault. I'm glad he pointed it out.