I've only really been nonplussed (as in, left and came back still bothered and unable to respond, rinse, repeat) by three anti-adoption blog comments, and that's pretty good considering that I don't hang with the ponies and pools set (someone who links to me actually described me in that way). As for blog entries, for some reason they just don't get my hackles up in a bad way. I think because posts are more meditative, more ruminative, more rhetorical, and generally even more responsible than comments. And if not, it's the writer's house, and she can write what she wants (and I can leave if I don't like it, and I often do -- one even said to aparents, "leave," so I did.) Still, these three comments really got to me because they shut me up/shut conversation down.
In all three cases I didn't know how to or whether to respond. To start or finish a fight in someone else's "home" doesn't seem acceptable, even if only to state the obvious (like, "that's really unreasonable." To ignore the comment and continue with my own seems awkward. To not leave the comment I'd intended seems unfair, to me and to the author I'd intended to respond to. What to do? I guess just be glad it hasn't happened often, take my toys and go home?