I am a postdoc and I have been talking to a PhD student about his research, as his interests are closer to mine than to his advisor's. He is generally nice, smart, and hard working. However, I think he has an unrealistic opinion of his own work.
He has written a paper and wants to submit it to the top conference in my field. (I'm in computer science, so we publish in conferences, not journals.) Unfortunately, I don't think his paper has a chance of getting in. His paper would be a long shot even for a second- or third-tier conference. His paper is also dismissive of prior work, which may offend the authors of that prior work (who are likely to be reviewing his paper).
What should I do about this?
It would be helpful to him if someone gave him a reality check and told him to rewrite much of his paper. However, it is not really my responsibility (or place) to do this. (I'm only two years more senior than him.) If he does submit, he will get a reality check from the reviews, but it would be good if he got some more "gentle" or "constructive" feedback.
I have limited experience with advising. Perhaps someone more experienced can tell me what would be appropriate in this situation. I feel like more than a subtle hint is needed.