For example, I was listening to an audio book the other day and the author mispronounced a word which got the audience laughing. Until that point, I didn't even know that there was an audience and that the whole thing was a live recording.
Another example might be that you find litter in a section of a street which is usually super clean. This gets you thinking about how the street cleaners do a really good job. Or imagine the internet connection at your house breaks down and you thus realize that it has been remarkably reliable for the past 4 years.
It's both about realizing that something is flawless otherwise and appreciating it.
Any expression, proverb, or single word is appreciated!