Quote - Just out of interest, to what degree would people say Poser characters are caricatures or unrealistic?

Are we talking about:

meshes?
morphs?
textures?
Poser's own material/lighting/rendering shortcomings?

Is it possible to quantify the degree to which each area is currently deficient?

If you imagine realism as a straight line between a photo of a real person and a drawing of a stick figure, where does a good Poser render (with a well morphed and textured M4, for example) come along that line, and what are the components of that render that typically in your opinion most break down that realism?

I think the DAZ meshes are perfectly capable of creating a "realistic" human.  And the morphs provided go a long way toward that end as well ... most especially when you also add morphs by Capsces, because they add some "quirkiness" and character. There are also some really good textures out there, so I'm not sure that is the issue. And as far as materials go, I think Poser is quite capable in that regard.

The problem is, there are few people who use these tools in the right combination. There is a popular "look" in the galleries, and the majority of the characters available for sale tend to cater to that look. Big eyes, flatter noses, and huge collagen-filled lips are very popular in the galleries, making so many renders look the same. I don't think I have never met a real person that has that look.

As far as proportions go, both in face and body, I think that is one of the main issues that breaks down the realism. Body-wise, the Millenium meshes have a small head in relation to the rest of the body proportion. Hands, too, tend to be on the small side. If you superimpose a render of V4 or M4 over a reference photo from 3D.SK, you'll see what I mean. Head size has to be increased. Torso proportions have to be adjusted. Hand size usually has to be increased. Breasts need work.

Then we get into the facial proportions. Ear placement. Forehead and crown shape. Eye, nose, and mouth height and shape ALL need tweaking, usually beyond what the provided morphs allow. Asymmetry also adds to realism. To do this for a character for sale might mean tweaking joint parameters for eyes and mouth parts, too, in order to make the figure "animate-able", and few have the technical knowledge to make that happen.

Textures and materials: Remove baked in shadows and highlights and use bump, displacement, and material settings to achieve the shadows and shine.

Materials ... though we are getting closer, that is the holy grail for most applications. Poser, DAZ Studio, Carrara, pretty much any other 3D application, skin IS the toughest thing to master and that is the element of the render that most often breaks it down and makes it "3D." Eyes, too ... the eye textures and highlights are usually a dead giveaway (no pun intended), and that is the area that most people look at first.

The lack of realism can't be attributed to any single thing ... meshes, morphs, textures, materials ... it's a combination of all, as well as the talent and skill of the artist behind it. A good realistic character takes work, but I think it can be done.