Just personal experience.
The predictive power: people who have "pro-nice" tastes in one arena of life ought to have "pro-nice" tastes in others, and vice versa.
I don't think that's the right prediction to try to apply this to. If you acknowledge it's a spectrum, then it must be true that someone who likes some happy things might not like other happy things.
It might be more interesting to look at other things outside of personal taste that points along the spectrum correspond to, and consider what conclusions can be drawn from that. (Do "anti-nice" people correlate to those who've had rough lives, or those who're imiting people who've had rough lives because it's "cool"?) That might get you clo...
EDIT: This post is pretty flawed, but please read the comments anyway: I'm hoping to rework it into something that catches the idea better.
You can view a lot of value differences along a pro-nice/anti-nice spectrum.
Pro-nice people (I'm one) gravitate to obviously pleasant, lovely, happy experiences. We like kittens and puppies and rainbows. We like transparently "happy" music and transparently "beautiful" works of art and literature. (If you like Romantic poetry and science fiction, but not contemporary novels, you might be pro-nice.) We prefer the positive social emotions, like sympathy, encouragement, and teamwork. We may choose intellectual interests based on the fact that they make our brains feel good. We tend to be drawn towards proposals for making the world wonderful.
Pro-nice people aren't quite the same thing as optimists. An optimist tends to anticipate that things will turn out well, or look on the bright side. But pro-nice people may well hold pessimistic ideas or have melancholy temperaments. Pro-nice is a preference for the positive. A typical pro-nice attitude is "Humanity may be destructive and cruel, but the one time when we're at our best is when we're doing science. Science is lovely. I think I'll be a scientist."
Anti-nice people have a preference for the difficult. They find pro-nice preferences saccharine. They like artistic expressions that have a challenging or negative "mood." They prefer the negative social emotions, like antagonism, sarcasm, and cynicism. They dislike things that have obvious appeal, or things that everyone finds pleasant. As far as social issues go, they take a keen interest in potential catastrophes and what must be done to avert them; they generally aren't drawn to proposals to "make the world a better place."
Again, anti-nice people aren't necessarily pessimists or unhappy people. Anti-nice people prefer to direct their attention to the challenging, the problematic, the worst-case scenario. To an anti-nice person, there's nothing interesting to work on when everything is going smoothly; just liking things or agreeing with people or being contented is rather dull.
I suspect that a lot of conflict can be summarized by the clash between pro-nice and anti-nice personality types.
Are you pro-nice or anti-nice? Have you experienced difficulty communicating with the other type?