Hmm.. I guess I'm wanting more realistic reflections.
I think most games are struggling with reflections right now (except the driving games).
"Right now"? SSR is a modern but unstable technique, and planar reflections have always been costly and lacked versatility. Games have always had issues with real-time reflections.
This is part of why stuff like The Tomorrow Children is exciting; GI and real-time reflections and whatnot result naturally from the lighting model, and aren't simply expensive hacks that operate
in addition to it.
The racing games so far that I've seen use them properly.
If you're referring to Driveclub, it's true that it tries to avoid cubemaps, but its alternative is to just incorrectly resample pixels (i.e. from the edge of the screen if it's trying to reflect sky). If you free-cam around in photomode, it shimmers like crazy, especially on bodies of water and such.
The reason Driveclub's SSR looks so good most of the time is that the racing cameras avoid a lot of obvious miss cases. The implementation would look terrible in a game like ISS.
Ok.
But how can we tell if it's a cube map reflection or an actual re-rendering of the scene, stored in a buffer, and retrieved via ray-casting (or however they calculate the SSR)?
Not really sure what you mean by "re-rendering of the scene." The whole idea of SSR is that the ray-casting
is the re-rendering; you don't have to "fully" render the frame again, like you do if you use a planar reflection.
As far as "how we can tell", I'm not sure what you mean. We can tell based on whether it's reflecting dynamic objects, and usually also based on how accurate the projection is*. In the case of the image I posted, it's reflecting a hall-of-mirrors effect that was clearly created on the fly by Delsin moving against an untextured wall.
*Even the best cubemap implementations still tend to have some wonkiness with how they move around, since each individual cubemap was taken at a single point and isn't entirely aware of how it should change with parallax. By contrast, most real-time reflection methods parallax reasonably correctly; the worst I've seen is Destiny's SSR, which has strange "corners" and such.