>They're defining a bunch of custom media types, which in of itself is pretty weird,
No it isn't. If you're doing REST and your resources are not completely trivial (arguably, even if they are) you should be defining a custom media type for them (think HTML5).
>but then they're not actually using those media types as the Content-Type of the response.
No it isn't. If you're doing REST and your resources are not completely trivial (arguably, even if they are) you should be defining a custom media type for them (think HTML5).
>but then they're not actually using those media types as the Content-Type of the response.
Ok, that is very weird.