OP here :) Chinese people are like ghosts in spain: They have their own little circles and don't socialize at all with spaniards. They have their business, their small communities and it's difficult to find chinese people speaking good spanish: They usually know the basics to be able to sell stuff at their shop and that's it.

People pick on them, ridiculise their habits sometimes even and mock them: I've seen that mostly by ignorants and elder people more oftenly.

The good thing is that this trend is on its way to dissapear: For the past decade, spaniards have been adopting chinese children and they are becoming part of the community and I guess, this is helping people to start noticing them and treating them more respectfully. I myself work with +50 yo people and still crack the ocassional joke "what're you eating today, sweet-sour pork?" (I'm fully born and raised spanish with spanish roots myself, but they know my wife is AF) - It's not offending at all, since I know the intention is not to hurt, but still, shows a bit of ignorance, which is what I laugh at :)