There are two variants of this behavior. The first is done in bad faith by people looking to score points. This is relatively easy to spot, and thus easy to ban. The second is the result of haste and passion--sometimes we're a little too eager to hit "submit." I rarely see the former, and would like to see a lot less of the latter. I'm sympathetic to how our emotions push us in these debates. But the fact is that asking people to contend with arguments that aren't actually their's is, no matter the motive, disrespectful.
Here some practical advice: If you find yourself doing more paraphrasing then actual quoting, you're running the risk of strawmanning. I urge people to use quotes liberally (the html is <blockquote> blahblahblah </blockquote>) Beyond that, I really urge people to do their best to understand the context, and the spirit of those they're debating, mostly because, without that, there really isn't much point. If you violate either of these rules by mistake, it's worth saying "My bad, I missed that." It won't kill you. On the contrary it's how you earn some credibility.
Talking past each other--intentional or not--is a giant time-suck. Do the community a favor and give your neighbors the respect that they're due. After that, feel free to take them apart.
This article available online at:
http://www.theatlantic.com/entertainment/archive/2009/12/against-the-strawmen/31404/
