When I was writing my dissertation, I turned in an early chapter for a grad seminar I was taking, to a professor who wasn't on my committee in any way. That professor, though, took the time to really read the chapter, and suggested a revision strategy that brought out the argument of the chapter way better. It was the best response to a piece of my writing I ever got, more insightful and revision oriented than any other, ever.
When I read advanced student work, I try to model myself on that professor. I try hard not to want to make the argument mine, but to help the student revise the argument to make it more effective at what s/he seems to be wanting to get at.
Tonight, I think I did a pretty good job. I suggested a reorganization, one that will be fairly simple to undertake, but that will restructure the whole in a way I think will be more effective. And I suggested that the student is trying to focus on X, Y, and Z, and if I'm right, the student should revise so that X, Y, and Z come through in the introduction and in ever section of the work.
The work is far smarter than I made it seem in my biking analogy earlier today, and I think with revision will pull away from the things that bothered me and get stronger as an argument.
It's weird, though, because I'm not the last word, and I sent my response to the last word person and the student both, so that they can both see. And now I feel sort of anxious that the last word person won't shake his/her head about what a total idiot I am and how could I possibly suggest what I did.