I don't usually chime in on matters like this, but what ought to be fairly self-evident is that the moment an argument becomes personal, you effectively lose the argument. Attacking a person instead of the subject is like admitting the evidence you're arguing isn't strong enough to win the day...in addition to coming across as petty and childish. Argue the argument,
not the poster. Take "you" and "I" out of the discussion and it generally stays civilized.
If a poster's ideas as absurd, a reasoned counter-argument will make them look more ridiculous than sniping at them.