Now that I read your reply again it seems I misunderstood it

So: After retopology in 3D Coat models preserve their connections with bones?
But why does it looks bad? What does retopology do? Blender's poly reduction script only cut's down vertex number trying to preserve model shape, nothing else.

I guess retopology process (in 3D Coat) finds nearest vertex to the place you draw squares and cut off all other vertex?