Of all the time I've lived in China, I probably have only seen counterfeit money once in my life. Do you have any evidence to back up your claim?

The person, we went to meet told us that counterfeit money is very common. I don't have any evidence.

Also most of the restaurants has the machine to identify counterfeit currency note.

Just out of curiosity, how would you know if you had seen counterfeit money?

That's a good point. I should say I've only seen the "low quality" counterfeit money once. The one I saw had similar texture as real money, but the paper was either thinner or thicker than the real one. I can't remember the details since it happened years ago.

There is a metal strip in the real 100 RMB notes that most of the copies don't have.

You can crinkle the paper money in your fingers. Real money makes a unique sound. It is perfectly acceptable to test the money in front of the person you got it from.

I had to use cash instead of WeChat a few times and the vendor also did this as a test.