Roxie's mesh isn't that bad. It's no Genesis, but with some refining, and not even all that much, it could get close. 

Left is default Roxi in her default pose with her arms down. Right is my rework WIP after a couple hours of adjusting posture, scaling and proportion, adding a couple of magnets, and doing some light brush work in ZB. Still has a ways to go, but I think this is a decent start, and an example of Roxi's potential.

Her mesh does need refining. There's wasted geometry in some places, and not enough in others. It's difficult to give her much muscle tone because the geometry isn't there to support it. Using SubD doesn't make much difference in that regard either. 

I think her mesh is a bit too low resolution, but until I actually look at everywhere that can have geometry removed and then added to other areas, I won't know for sure. 

I'm thinking about reworking her geometry and re-rigging her after I get her shape finalized. 

 

~Shane