I want to float what's perhaps a controversial opinion to see what everybody's thoughts on the matter are. The general consensus is to try and be polite at all times. However, I will argue that there are necessary limits to politeness and that it can be counterproductive at times.
When somebody makes a comment in good faith, I think it's important to engage with it in good faith. If there is a disagreement then it can be articulated in a clear and polite manner. The hope is that the discussion will be productive and everyone will learn something in the process.
On the other hand, when comments are made with the intention of trolling then trying to engage them as if they were made in good faith only plays into the hands of the troll. Addressing the points that the troll makes as if they had merit implicitly validates these points as if they need to be debated.
In my view, the proper response to trolls is ridicule. They have to be called out for what they are and we should not take the bait to attempt starting a debate with them. Instead, it's better to simply make it clear that the opinion is garbage and not worth discussing.
The argument against being snarky is that it can drive people away, but I don't know that there is much weight to that in practice. Anybody who's read Lenin can see that his writing is full of snark, and he often ridiculed opportunists and revisionists. Clearly that didn't hinder the Bolshevik movement all that much.
I think it's important for us to express confidence in our views, and to be assertive about our positions. The facts are on our side, and we don't need to act as if our position is the one that needs defending.
Amusingly, I had plenty of libs screech that I'm spreading Russian propaganda when I link to western mainstream sources that say things they don't like to hear.