Question for fellow Mandarin learners 向各位学普通话的伙伴们提一个问题
To you, when does one become "fluent" in Mandarin? Is it gaining a HSK 5 and moving onto HSK 6? What if you never do the HSK exams, then what is the criteria for calling oneself "fluent"?

对你来说，到哪个阶段才能说某人的中文流利的？是已获取汉办5级，再快要考汉办6级的时候吗？假如你从未考过汉办，那么为了证明你是中文专家，条件应该是什么？

Question

Question for fellow Mandarin learners 向各位学普通话的伙伴们提一个问题
To you, when does one become "fluent" in Mandarin? Is it gaining a HSK 5 and moving onto HSK 6? What if you never do the HSK exams, then what is the criteria for calling oneself "fluent"?

对你来说，到哪个阶段才能说某人的中文流利的？是已获取汉办5级，再快要考汉办6级的时候吗？假如你从未考过汉办，那么为了证明你是中文专家，条件应该是什么？

Answer

1）可以用一些native才用的词，能看懂中文社交媒体里面大家在说什么。 
2）无障碍交流

Answer

If you can understand when the other person speaks, and If the other person can understand what you say, then you are considered oral fluency.  Same thing for writing but that's another different story.

Answer

If you post comments on a Chinese forum but raise no one's suspicion, you are absolutely fluent in Mandarin. I've encountered one.

如果你在中文论坛发帖而不引起人们的怀疑，那么你的中文就非常厉害了。我就遇到过一个。

Answer

我认识个越南小伙，他说他汉语四级半，我对他挺满意，我们俩可以无障碍交流。

Answer

This question is more suitable for CSL learners and I think the asker has been so intending it. So Chinese native speakers might as well keep a lit away.