"You must know that this referendum was approved without reading the bill in the Catalonian parliament, so the opposition couldn’t even have a say."

It's understandable given the filibusterism, and outright prohibitions you would expect from the central government. Referendum has been proposed for 7 years and it was rejected every time.

Catalonia has less corruption than Spain in average. Even though the National Police and the judiciary have a very strong bias in favor of spanish parties.