This is sarcasm, but people unfamiliar with Copenhagen might not be aware. Some historic buildings use this shade of yellow, produced using iron vitriol (iron (ii) sulphate) and whitewash.
It's not sarcasm. I'm voicing an opinion which -- despite the vast majority of people preferring grays blacks and whites -- is considered uncouth and offensive. I've seen a few articles like this discussed recently, it's apparently considered a bad thing. It's sign of how dreary people are, or how they've become cogs in the corporate machine, or some other portent of how much worse the common folk are.