I also do this for situations where the article sounds like fluff or link-bait, but involves a subject where an intelligent conversation could occur amongst smart people. There are lots of times when the comment threads are more valuable/interesting than the links.

I think I do the opposite. If it sounds like it's going to be ridiculous/controversial/unusual I like to read it myself first and see what my unbiased thoughts are. If it sounds like something easy to agree with I usually just want to see if anyone has a unique perspective on it.

I guess it's a good method of second-level quality control. The fact that its on HN is usually a good primary check, so supplement that with good comments and the resulting link is usually a great read.