There are good players and there are bad players. If you stick to one server you are likely to start seeing the pattern and avoid the bad ones. Doesn't matter the language or anything else. I've had various players in my parties and some of them were good some were bad some were just crap. Some were actually willing to listen and improve themselves while others ragequit. Some would keep trying even with no progress while others would progress a bit in all that time. And even the bad players can surprise you at times(and I have experienced all of the above).

Welcome to the boiling pot that is the internet/an MMO.