Based on my question Please put more thought into migrating questions to other stack exchange sites and the linked question Please don't migrate low-quality questions to other sites, It was suggested in the comments that I propose solutions instead of merely complain.
So I wonder, would it be possible to implement a feature request so that questions that are migrated to another stack exchange site and then promptly (a day? a week?) closed as Offtopic (and possibly, subjective & argumentative) should cost the people who voted to move reputation.
This should have the effect, hopefully of penalising people who migrate to another site without fully understanding the target site, without imposing penalties on people who move questions which do belong on the target site.
It should hopefully mean more bad questions are closed rather than moved, and also that any borderline questions aren't moved so quickly, so the person asking them can clarify them and then get their question either answered or moved as a good question.
As per Ben and Bill's comments below, the penalty should be just a couple of points per bad question and should be 'saved up' and applied only to people who have made a series of bad migrations. I hope to discourage bad question migrations, not penalise people for making the occasional honest mistake.
I appreciate similar questions have been asked/proposed before but all the ones I've seen have talked about moving questions always costing reputation, whereas I'm proposing a feedback loop: only bad migrations, as voted by the target site, will cost reputation