Have to disagree. I had a blackhat/gray hat site go from almost 2k uniques per day to like 25 uniques a day after the Fred update. They have no problem crushing your traffic right away.

Censorship is a different story. They can slowly bleed you out, but if you notice your metrics are dropping (especially with 3rd party analytics) this would tip you off.

Also, why would they send you “low quality” traffic from another country? This doesn’t make sense, and would be easy to call out from 3rd party analytics.