Sometimes these are bad, usually not. It's difficult for me to outline exactly what kind of disclaimers are bad because I think they're bad whenever they do more to prevent the earnest engagement of ideas than to help it, and determining which category specific cases fall in depends a lot on contextual things that I'm having a difficult time describing.

I know it when I see it, basically. It's easier for me to ask you to make recourse to your own experiences than it is for me to describe these kind of situations all by myself. Personally, lots of the time when I'm writing comments on LessWrong I spend about 30 seconds thinking up the points I want to go over, and then a couple minutes figuring out how to communicate that message in such a way that it will actually be persuasive to my audience. I feel like I spend much more time here trying to "dress up" my comments in the jargon of the site than I do actually learning things. I expect that many other people feel similarly or at least empathize with and understand my perspective on this.