Lighting -- though not necessarily natural outdoor lighting. Could be studio style, or Hollywood style too.

Pose -- otherwise the figure will look like a mannikin. I think this is the most difficult thing to master

Hair -- usually glaringly unrealistic

Clothing -- most conformed clothing doesn't drape realistically

Architecture/Environment -- there needs to be consistency in the texture resolutions

Unless it's one of the really low end character sets out there or has truly awful shaders, the skin is probably one of the last things that I'll notice, unless it's a very close up (all face) portrait. After all, I'm used to seeing extremely fake looking skin whenever I pick up a magazine or even watch a movie.

The problem with the extremely close up portraits in Poser is that facial hair is always absent in females. Yet, even in the most airbrushed cosmetics ads using real photographs, the models almost always have some visible facial hair (I don't just mean eyebrows) unless the photo has been filtered and blurred or the lighting blown out. Trouble with many close up Poser renders is that the other features are crisp, and you can see the pores with great precision. If you can see the pores, you should see the fine little hairs, especially on the cheeks and around the jawline.

---

PoserPro 2014, PS CS5.5 Ext, Nikon D300. Win 8, i7-4770 @ 3.4 GHz, AMD Radeon 8570, 12 GB RAM.