If a first time asker has an SO account that was recently (say, within a week) question blocked over there, how about showing them a warning like this:
Wait! You've recently been blocked at Stack Overflow. Consider that quality requirements at Software Engineering are similar. Note that Stack Overflow topics are not covered here and that your questions can't even be migrated to Stack Overflow because of the block.
This hopefully would help them avoid further frustration if they get down and close votes, angry comments, blocked migrations and question block over here.
Per stats, Programmers appear to be most popular of SE sites among this category of askers. After being blocked or scared by warnings at Stack Overflow they simply try to dump their low quality stuff over here...
SE might want to think about how to improve their UX in order to educate during question composition...
efforts in SO close vote queue make me think that quite a lot of users started hitting the question ban there... how many questions per day are posted by users that were banned at SO less than a month ago, and how many of these questions end up closed / deleted?