Quote - But why should I care whether the colour is processed correctly?

first of all, most of us can tell.  it's, imho, glaringly obvious in most works, including my own older heavily processed, filtered and even painted works.  we begin with the question to verify. 

second of all, it's like any trouble-shooting. you begin with checking if people have the right settings.  answers change based on how they respond.

Quote - If it appears correct, what has its actual correctness got to do with anything?

this question makes no sense.  if it appeared correct, even just to them, they wouldn't ask for help improving it.

Quote - We have people using lights without shadows. How does that fit into correctness? It doesn't.It's an attempt to give the appearance of correctness.

which is why most of the time, even before "did you use GC," we ask whether they have shadows turned on.  even if it looks like they're using lights with no shadows, people ask and check. 

and since lots of people use lights with no shadows to try to accomplish the same thing GC does (that's not a guess, i've literally been told that), that's yet another example of how you need to change your lighting to stop compensating.

Quote - We have figures with gross anatomical flaws and faulty joints. We have skins and flesh that doesn't react to surface collision with other objects. We have muscles that don't flex when we change figure poses. Spines with 2 joints. And let's not even talk about hair.

None of those things is even close to correct. Wherefore the obsession with this one other thing?

it's not an obsession.  it's simply addressing one of the many problems we can.  just like phantom3d and odf are addressing the problems they can with their figures.  just like most of us using linear workflow use bagginsbill's fresnel equations.  i use Matmatic now (for lots of reasons), and i can generate lots of different materials quickly and easily.  i incorporate features like conservation of energy, accurate fresnel equations, and linear workflow automatically for all of my materials.  i rarely think about them at all.

light is the common denominator in visual art.  no matter what genre, people expect some connection to how light works in real life.   not using linear workflow is like applying a random, extreme curve filter to all of your work.
at the end of the day, the proof is in the pudding.  not just according to anyone in this thread, but people in general.  bagginsbill is a "guru" for the very simple reason that when he posts his results, people like them.  they want to do the same thing.  they pay attention to what he says only based on his results and of those of us that use his advice, tools, materials, etc. 

some people want to get as far as they can with realism in Poser, and i think most are less satisfied with lighting and materials than figures, clothes and props. 

there are no nodes that can work correctly with sRGB input.  there's no way to tell someone the correct (or as correct as possible) way to make anything without linear workflow.  what bagginsbill knows is physical accuracy, and that's the basis for advice he gives.  it's fine to ignore his advice, but those that follow it make their choice based on renders, not hype. 

those of us that use linear workflow do so because it solves a problem for us, and solves it efficiently.  many of us can see a clear difference.  if you personally can't see the difference, or don't want to learn to work with it, don't.  everyone posting to this thread  who uses linear workflow is saying not to use it if you don't want to.  what response are you looking for?  that we shouldn't use it?  that we have no reason to do so? we do.  we found that it improved our work.  as someone who heavily postworks, i found it worlds better to have a more realistic base than one where all of the shading is just plain wrong. 

please stop making strawman arguments like  "you can have realistic results without GC," which we acknowledged from the start, "if you like how uncorrected workflow  looks, why change it?" which we never suggested, and "this is against artistic license, stylistic extremes and postwork," which none of us has said and many of us use.

instead of just saying there's no clear explanation, could you say what's wrong with any of the explanations so far?  just to reiterate.

• all digital images that don't explicitly use another color space and all monitors, digital cameras, cell phones, etc. (which means the colors displayed in your color picker) work in sRGB space. 
• all renderers work linearly.
• if you don't translate input to linear form, the calculations renders make are incorrect.
• if you don't  translate the rendered result to sRGB, the monitor can't display those calculations correctly.

this is not a simple case of lighter/darker or more/less saturated.  all of the shading is off, and both highlights, shadows and everything in between are incorrect in different ways.  highlights are too bright, shadows are too dark, and the shading between them doesn't progress properly.

GC equations are simplified approximations that will give you visibly lightened shadows compared to using sRGB equations.  they are themselves not quite correct.  i actually saved bagginsbill's tests, and he once gave me permission to repost them at another forum, so i think i can repost them without totally stepping on his toes if people are interested.  i can't find them to link to.

GC in Poser Pro affects all color input. that includes colors for procedural textures.   bagginsbill rarely uses textures, and pretty much only does so on human figures.  if you notice, his most recent material posts don't include GC because he's using PP 2010. i'm pretty sure that you actually have to be careful about GC and intensity maps that you want to leave as is.