Jay I agree with you completely. There is never any reason for such combative attitudes here, any other forum, or anywhere in life. I don't mind a little hard-play in a debate, it's good for people to put up a fight for their ideas, but to make it personal is to lose track of the whole point of it... That's just a lack of maturity.
My suggested solution is to not bother with any sort of degradation. As Bernhard would say, "to fight evil is to give it power".
What I've found to work in other forums is to give someone the benefit of the doubt if they're being negative... Take their point into account, ignore any attacks (sometimes I have to grit my teeth, heh), and direct the conversation back to somewhere useful while showing them a basic level of respect for their perspective. I've found this works most of the time, and sometimes, because of my refusal to play any disrespectful intellectual battle, I find I'm the one with the wrong perspective - a lot of the time my 'opponent' is actually in agreement! If someone's just not willing to be respectful and only seems interested in 'winning', might as well not bother with them and make replies for the ones making a contribution.
What really gets me though is when people hide in anonymity and never reveal themselves. I can only talk about information and debates so much before I get bored, but I don't get bored with people.
That's why Pianistimo is so interesting - she doesn't hide anything, you know you're talking to a human being! That's more valuable than any witty arguement.