[croon]

I don't moderate anything anymore, but I generally have an n strikes policy when debating with someone.

If I spend [not insignificant amount of time/mental energy] with you just to disprove something inane, and you do that to me n times, I won't argue with you anymore, even if the n+1th time happens to not be completely baseless. At that point it's either explicitly on purpose, or implicitly linked with a bias that makes them susceptible to bullshit that confirms said bias.

I don't know if there's any ab initio way of knowing if someone's spouting nonsense on purpose or not, so character patterns are hard to scale. But that's why moderation online is harder and faster than in real life, because you don't have a 1on1 interaction in the same way. It's up to netizens to behave and think before speaking.