Should I posted my oppinion in English?
Although my English skills are not good, I hope that you can understand my oppinion.
I think it depends on the person or the situation. There are some options we can figure it out. It is possible that the people who you asked something might speak English well. And actually, most younger generations want to speak English well and when they meet a foreigner or if they give a question from a foreigner they don't really like answering with Korean because they don't want to be appear to other person like a man who can only speak with Korean.
Anyway, I want to recommend a way what you can solve this problem. If someone answer in English for your question, even though you don't understand thier answer at all. You will be trying to say them, "I can understand Korean as well."