This came to light thanks to Kristy–the thread is here.
Basically, MTurk does not update the state that people live in when they move. So if I signed up to be a Worker when I lived in Massachusetts, and then moved to Oregon, MTurk still has me listed as a worker in Massachusetts.
As someone who has done a few studies using state of residence as a requirement, this is a HUGE problem. A lot of Requesters are doing political research now, and this makes it a HUGER problem.
The post provides some good ideas for work arounds–the best one is doing a one question HIT asking for the state where someone currently lives as a qualifier and then doing an invitation only HIT or using that a qualification.
Yes, Amazon knows about it. No, they don’t seem to care.