OK, my two pennies worth.
I think a good rule of thumb for civilised discourse, is 'play the ball, not the man'. Bad ideas exist to be destroyed (through rational argument, evidence etc.), but people are due some respect.
"That's a bad idea, and here's why ..." is fine. "You're an idiot" is not.
There are a number of logical fallacies that are occasionally produced, in order to undermine someone's argument. Some people could do with familiarising themselves with them, and avoiding their use in future. There's plenty of resources on the internet.
Where we're dealing with subjectives, or a topic where definitions are lacking or otherwise unclear, expressing a different opinion doesn't make you wrong. Some people could maybe do with a reminder from time to time.
Generally though, LuLa is pretty tolerant & grown up. Far more so than some places i can think of. Soft-touch moderation seems appropriate in the main.