I certainly seek to resolve points of disagreement, through engaging with folks with differing opinions, as you well know from experience. I reckon that reveals I consider them qualified to have opinions, and that I value their personal opinions enough to undertake discussion I hope will result in consilience.
There are few folks I don't think are qualified to speak their opinions, and those are just trolls, whom I might even agree with. I don't understand how I disqualify folks who disagree with me. I fairly often change my opinion because someone disagreed with me and proved they were right to my great benefit.
I mistook some of @lordbutterfly's statements as trollery, but later realized he did simply disagree. My earlier dismissal of his commentary was due to the fact I thought he was unwilling to consider the evidence. That's just trolling. However, when he pointed out he did consider the evidence but disagreed with me, I changed my tone.
Poisoning the well works very well. It's not an argument though. As you state, it's a tactic that degrades discussion rather than improves it IMHO.