Why does Bohemian denote a disorganised lifestyle?

During the eighteenth and nineteenth centuries most people in the southern Romance-speaking countries (Spain, Portugal, Italy, France) supposed - incorrectly - that the Romany people (Gypsies) originated in the Cechy area of central Europe.

As a result, the term Bohemian became synonymous with the term Gypsy:- that is: rootless, poor, and irresponsible.

Henri Murger's 1851 novel Scenes de la vie de Boheme broadened the term to refer to the lifestyle of the new European urban poor:- Puccini later based the opera La Boheme on this novel.

Of course, the Romany lifestyle is nowhere near as chaotic or poverty-stricken as the petit bourgeois imagined it to be - but popular culture has never been famous for its exact grasp of facts. (You can compare the 1920's US prejudice that Mexicans were permanently stoned on marijuana).

But Bohemian became a universal word for 'gypsy'; 'gypsy' became a term for poor, dirty and irresponsible.

And the Czechs became the most anti-Romany people in Europe.

.....

Many people imagine that because the Czechs are a neat and order-loving people they must be 'easily governed'.

Reinhard Heydrich made that mistake, so did the Soviet Union.

Just read a very good article on just this topic.