I don't ever contribute to the threads that descend into what the OP describes. I do read them and whichever side I am on I don't comment as it adds nothing apart from reply counts!
I came to Flyertalk thanks to a Google search query I had on a why an aircraft type had changed... it was answered and I stuck around! I use the forum to gain loads of awesome information (and cheap fares to boot!) and feel I contribute helpful responses when I can.
I like the banter that exists between some of the more regular posters and really detest the personal attacks that people keep descending into - not just newbies but some long term high count posters.
If you've got nothing helpful to say... then say nothing!