Is there any policy about it? As of lately, I have seen requests for reopening questions which seem homework, but have no "homework" tag and show no effort by the proposer. Let's say it's like someone just poses the question, hoping some kind soul answers it, but does not bother to check.
I don't know if the rejection (no, sorry, the put on hold) message in these cases explains the proposer what (s)he can do to improve it: but anyway it would be nice that if no further comment was added, such questions should remain closed. Or not?