It's important that we disallow SO to push trash to us. Engage on these questions on MSO:
Programmers is about to go live, which questions should we migrate?
Multiple duplicated question on SO are being migrated to PSE partially
Migration questions from SO to PSE just to stay temporarily
Please stop using Programmers.SE as your toilet bowl specially this answer: Please stop using Programmers.SE as your toilet bowl
In general, I have been deleting the questions that I think have no lasting value.
The only ones I want migrated are the ones that are useful.
I'm glad you brought this up. I have no problem with questions being migrated. There are some question that have come already that do belong here, such as:
And then a question that is off topic (too localized) for any SE site: Programmer's Wages [closed].
I think that perhaps as the "newness" of the migration path wears off we will see less junk questions being dumped here. That being said, I'd wait a week or so before doing anything off-site. If this continues, we need to open a new discussion on meta.SO about the issue.
As far as what to do with junky questions, CLOSE THEM! They aren't doing us any good open. If they belong on another SE site such as webmasters, etc., then certainly migrate them, but kill it otherwise. If they are of no use, delete them. No reason to clutter our site up with other site's horrible questions.
Please visit the links @bigown has posted. Even if you don't have anything to add, vote up the answers present the best solutions with P.SE's best interests. (and vote down the bad ones!) "If you don't vote, don't complain" - be heard!