Well, it's good he's selling more models, but of course, work needs doing on these models. Perhaps if you observe models in games from a 'how do I do this?' point of view rather than looking at a picture and
thinking 'how do I make a realistic looking low poly model?' (although literally I doubt that's the approach, but I'm just trying to bring about a point).
Also, with texturing not many people slap photos on, they can cause problems and inconsistencies, people may use a clone brush on the skin (or a custom photo brush) and pay attention to details on a person model and paint it. They may even use body parts, but some of the detail still relies on the model, even if it's low poly.
Just a few comments and pointers when approaching humans, though good luck with Arteria and your 3D modelling endeavours.
I shot the sheriff