Did Facebook change their system for test user accounts?
http://developers.facebook.com/blog/post/475
I hate to break form and answer my own question, but from the comments enough people seem to be having this problem.
Digging through the developer updates today I finally found the above post (having already written workarounds, of course) Quoted:
We have removed the ability to turn user accounts in test accounts as mentioned here to prevent unintentional conversions of real accounts into test accounts. The proper way to create test accounts is by using the accounts connection of App Graph Object.
This tiny notification was mixed in with the updates for March. Probably should RSS their developer blog so these things don't take me by suprise again! This particular update became effective March 4th. In any event, it's good to have a conclusive answer right from the source.