Is it a good idea to answer to those who have crazy non-science based ideas and won't listen to our criticism?
I think discussion can only be possible if there is a common understanding not only about the topic but also about the kind of communication we'd have. Discussion means there are at least 2 parties and both sides should help each other make the discussion productive.
It requires some level of psychology from at least one of the parties.
For instance, I'd make a speech in front of friends who know already a great deal, but they are friends. I'd draw their attention by making them laugh, using humor (I hate it when someone falls asleep, but you can't avoid it:-); otherwise, if it's in front of young children, I'd mimic acts (like what it's like to be in OG); of course, you won't try to explain the Sun's bipolar magnetism to 8 year old guys; that's also an issue.
I think mr Plait should not bother with people who are rude; he's right; I also don't understand why Dan keeps after James; but that's his decision. To communicate must be rewarding somewhere, otherwise don't bother.
Raoul