Suddenly the real-time visitor increased to +50 on a single city, the traffic source is / referral or other google translate site like / referral, etc

After the peak was gone, it left pages / visits = 0.01, Avg. Visit Duration = 00:00:01.. Obviously it's just a single visitor, but google analytics recorded it as +100 visits. Such case seriously polluted my analytics data.

I am wondering if this is a risk to my site? or anything I can do to avoid such wrong data recorded by google analytics.