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!
Best Answer
This isn't the general answer you're asking for, but was too long for a comment: An excellent example is the Persian Flaw, the namesake of which was when Persians, while weaving rugs intended to be perfectly made, would intentionally add an 'imperfect stitch' or other minor imperfection to honor and demonstrate their spiritual belief that humans can never be perfect.