When is Poor Man’s Dependency Injection appropriate?

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I can think of one other - in training.  Showing PMDI as an introduction to DI is hugely accessible - pretty much everybody gets the concept straightaway.  It's then pretty easy to show how it degenerates so quickly, which really makes them appreciate what an IoC is bringing to the table.

I can also think of another one: writing components that should be used as “black box” in other applications? You do not necessarily want to have the users of your component having to cope with all the mandatory wiring to get the component working.

What’s your view on that subject?

@Michael: Hard-code the wiring into the component's entry point. Black-box exterior with DI goodness.

what's about custom attributes?

Perhaps a more apt name for the pattern being described would be “Specification-only Dependency Injection” given that this pattern manifests itself in projects which employ unit testing without relying on Dependency Injection during normal use, and because no dependency injection is performed during the application’s normal use … poor or otherwise.  

Concerning the question of appropriateness, I might consider this pattern acceptable for new development in some circumstances, perhaps for small utility applications, etc., but such an approach should certainly be reconsidered at the point more flexibility is realized, or when the size of the application starts to grow beyond the size that a moderate refactoring session could alleviate.

I would also say it’s an acceptable pattern for tutorial applications, spikes, or prototypes (unless it interferes with the objective of the application), but if an application is purposed as a reference implementation then it would be more appropriate to show real-world usage scenarios.