Thomas More's Utopia is arguably the first science fiction ever written, because the piece is effectively people living in a perfect world. Plato's Republic doesn't count because it's a treatise on how to create Plato's vision of a perfect world.
The fact that I find both these perfect worlds horrifying is actually not that uncommon: no matter who builds a perfect world, we imperfect humans will always go and mess it up. On top of that, my idea of perfection is not going to be someone else's - quite possibly anyone else's.
So naturally, any kind of utopia is actually going to read as a dystopia to most people.
On the flip side, dystopias have a long history in literary, sometimes as moral lessons of the 'if this continues' type, satires, and of course the mess the heroes have to try to fix.
Okay, this ramble does actually have a point. Just let me find it again. Oh. Yes. Literary utopias are usually a resounding failure because either they're assuming humans... aren't, or because they just can't work with human nature. Or - more usually - both. (Funnily enough this applies to political utopias too. Whodathunkit?)
How often have you read about the idyllic lifestyle of this or that people and thought there was no way that kind of society could work because people just aren't like that? If you're anything like me, it's more than a few - but if we sat down and compared notes, there's a good chance that you'd like some of the ones I hate, and vice versa.
So, let's take a look at what makes a Utopia/Dystopia.
Start with the theoretical one size fits all, which in practice quickly turns into one size doesn't fit anyone very well and doesn't fit some people at all. If you're one of the ones that it more or less fits all right, you can probably live with the place, but if it fits too badly or doesn't fit at all the place quickly becomes sheer hell (this, incidentally, is one of the reasons I loathe pantyhose. I'm in the 'sheer hell' group). Not even clones will flourish in a monoculture - there will be enough experiential difference to ensure that some are misfits.
Now add human nature, which isn't changing any time soon. We're social critters, with all that implies: namely hierarchical and with deeply ingrained enforcement behaviors. Whether they're instinctive or not isn't relevant, because they're so strongly wired that they might as well be instinctive. No matter how you raise your kids, how carefully you keep them from the whole notion of competition and leaders and such, within seconds of meeting a new person they're sizing that person up and figuring out where they 'fit'.
When you watch someone - anyone - meeting a new person, a lot of what goes on in the first few seconds is working out whether that person is above, equal, or below in the social hierarchy. If the two have different ideas of who belongs where, there'll be quite a bit of work on the part of whoever thinks they should be superior (i.e. both of them) to establish superiority in a way the other recognizes. The winner will stand a little taller, the loser slump a bit - and as often as not neither one is consciously aware of what just happened.
That covers the leaders and followers (shepherds and sheep). There's two other very general 'types' you'll find in any large enough group. They're rarer than shepherds and sheep (this is why you need a larger group), and both of them will get attacked by shepherds and sheep if they reveal themselves. Predators (wolves) are kind of obvious. They pretend to be sheep so they can profit from other people. And no, this does not mean profit per se is evil. Using other people is - if you get all the benefit and don't pay any of the costs, you're a predator. If it's a crime with a victim (and yes, this includes running a company into the ground to get everything you can from it then walking away and leaving a bankrupt company and thousands of ruined lives), it's a predator thing. So is mooching off someone all your life - although that could be argued as a more parasitic behavior.
Then there are the goats - the independent-minded explorers and questioners who won't go with the herd unless they've decided independently the herd is the right place for them. No-one likes them: they often identify predators first, they make the sheep uncomfortable, and they question the shepherds. This is why you get a lot of misfits in certain areas - they identify each other and band together for their own protection. (As a side note: the USA is a nation settled and founded by goats. Over 200 years after the war of independence, that still shows - and is why the other 'colony' nations have the most in common with the USA. It's also why a heck of a lot of the inventions that materially changed people's lives originate in the former colonies. Penicillin: USA and Australia, cars: USA, planes: USA, drought-resistant damn near anything, Australia (Yes, I've left a lot off. It's not meant to be exhaustive)).
There is no such thing as a society where even all the sheep are happy. The best thing you as an author can do is build something that mostly takes into account human nature and has a whole bunch of incentives that tend to guide human nature towards improving things for their fellow-humans rather than destruction or power games (trying this in real life tends to end badly. We're perverse critters).
Some of the best fictional societies are - of course - Pratchett's, which take all of the variety and perversity of human nature into account. Sarah covers some interesting ground with Eden and Earth in DarkShip Thieves, and what Dave does to all the cultural myths about who is superior, the noble/innocent savage, the simple religious folk, the - oh, the heck with it, what Dave does to practically every cultural myth ever in Slow Train to Arcturus has to be read to be believed (if you haven't already read it, go and buy it. It's worth it.)
Who else has good fictional societies? Conversely, whose alleged utopias horrify you?