It's sort of two-sided, I think. It can be fun to figure out _meaningful_ patterns in data. I don't really find it fun to figure out that "so and so didn't use software that understood NA values back in nineteen tickety two, so some NA values are NA because they're newer, and some NA values are 0 because 0 is just like NULL in somebody's head, and some NA values are -999 because that was a thing they did in the Before Times."