We have been inundated with worthless spam, 99% of it from the PRC. I have tried to file abuse complaints, but these providers don't even have an abuse channel.
In response, I am in the process of blocking all ip's assigned to China. I've only blocked the most active to date, about 30%. This has had a very positive effect, spam is down by more than 50%. We haven't had a legit poster from there in 4-5 years. So no big loss.
If anyone has a problem with this, take it to the Chinese, when they clean up their act, I'll reconsider.