First of all, the word
utopia itself means that it cannot exist.
u=not + topia=society. utopia=A society that doesn't exist
A
Eutopia is a society that is in perfect harmony but the Greek's realized that a perfect society is impossible, so they used utopia and it caught on.
Read "Brave New World" or "1984" for a good view on a dystopia, or a eutopia gone wrong.