There is a tendency for people to be most irritated by negative qualities they personally posses, but can't admit to themselves. I think it is important to step back and ask the hard question about oneself whenever we find a quality especially irritating in someone else.
Judging other people is far more often inaccurate than people tend to believe, I think. It feels better to assume we can make quick judgments and be correct - it makes the world feel safer and more under our control, but the truth is that it may not be possible to comprehend anyone else's life. Any judgment we make is done without all the information because we haven't lived that person's life. Because there are so many holes in the information, the only thing we can do is fill those in with our own information. This is why judgments on others say something about our own self - and sometime the judgment says everything about us and nothing about the other person. Judgement is a close brother to hypocrisy. They co-exist.