I think it's a good list with the addition of layman's item:
you do everything on that list and nonetheless adamantly deny that you are in a bubble.
I've stated before that the primary value of A2K for me is as a means to hone my thinking.
Along the same vein as maporche, when writing a post I often try and anticipate the counter-argument that will be made and pre-empt it. If I can't come up with a satisfactory counter to the counter-argument, I will usually scrap what I've written or rewrite it. In doing so I learn what ideas to scrap as well.
Clearly this is not a regimen I religiously follow. Sometimes passion overrides the process and quite honestly, so does limiting comments to aphorisms.
I know that quite a few people have a problem with my longer posts, but frankly that's tough on them. They can always thumb it down to make it go away, and since most of the people who complain about them regularly thumb down posts of mine in which I might simply right "Welcome to A2K" or "Have a nice day" there's little incentive to shorten them.
Believe it or not I do often edit the longer ones (they could be longer!) but sometimes I get lazy.
However, I have found that the longer posts often contain my most successful critical thinking; particularly if I am responding point by point to someone else comments. I try to do this whenever I respond and it leads to length, but I have a problem with cherry picking comments for a response. Anyone can find something in a post to which they can fashion a counter-point (especially if they deceptively edit it or take in out of context which is too often the case here), but unless the post contains nothing but gibberish (which fortunately is rarely the case here) I think it approaches intellectual cowardice to respond to only one or two points out of the eight or ten made because you find you don't have a good response for the others.
Responding to all of them will often lead to one or more "Good point." or "I agree with you here." or even "I don't know enough about the subject to respond to this" and there's nothing wrong with that unless you feel compelled to never agree with an adversary, admit you are wrong, or admit that you don't know all of the facts.
So while I don't hold myself to it 100% of the time (or maybe even most of the time), I think a good rule of thumb for critical thinking and meaningful debate is to try and respond to every point someone makes, not just the ones you think you can knock out of the park.
It's interesting that anyone should play games like responding to only the points they can counter or, worse, manipulating someone's words. It's not as if any of us are being graded on our posts or receiving points in a contest (the thumb feature, as used, is a total perversion of a point system). A tiny, tiny slice of the world sees what we write, and quite frankly, praise from other members, while I'm sure is always appreciated, is pretty rare. So it would seem we are mostly motivated by self-regard. If we write something of which we are proud (it's persuasive, it's eloquent, it's witty etc) our sense of pride is our main reward. Since plenty of people cheat when they play solitaire, I shouldn't be surprised that they cheat
when they play the A2K game.