If I may add my two cents, this discussion can be boiled down to braking bad's quote: "after all, how pure can pure be?"
For most people 96% purity is more than enough and for some people difference between 96 and 99 is not just noticeable it is like tremendous gulf.
In my yesterdays "trivial bathroom"-scene, I again could see that it is not about "96% or 99%". :)
It was simply impossible to get a decent lighting and material look with the on-board tools in Corona.
Tweaking in PS Cam Raw was necessary, in order to get something out off the dull, raw render.
One can of course argue that it is the same with real RAW pics out of pro cameras.
BUT: sorry, 3D render engine users who need to meet client deadlines would have an easier life without massive post production.
In most cases, it is okay what comes directly out of Corona engine.
However, in this case of shitty, small room with sand colored tiles, etc. Corona clearly seems to meet its limits.
And yes, I also tried artificial lights inside the room... looked even more unnatural, despite trying different tones - from white to whatever, IES and non IES lights, etc.