That's probably because the Scrab has two key differences to the other characters we've seen so far:
- It has much, much more detail in its body structure, i.e. lots of muscles and crevices in its torso and legs, and
- It has much less detail in its textures; it's pretty much just two colours, with no patterns or anything.
As a result, it's much harder to trick the eye into thinking it's super-hi-res-CG-quality, compared to high-textured Abe and the low-detail Paramite.