I have found that perhaps the truest measure of humility is how someone handles attempts at correction - BOTH correct and incorrect attempts at correction.
To me, the key is the ability to step back and look first for understanding of the criticism. In other words, when I am rebuked I try very hard to ask myself how that rebuke is appropriate - to really spend time considering it, not simply asking shallowly and moving on.
Always, when I am able to take that approach, I learn something that I need to do to be better - something I can improve about myself. This is true even if I reach the conclusion that the original criticism was unfounded.
It's the same approach I try to take whenever I hear someone say something with which I instinctively disagree. When I force myself to stop and consider what part of the statement (or sermon, lesson, etc.) might be valid and valuable, more often than not I end up learning something as a result.