I've been trying to nail down a good corrective morph workflow lately and here is where I am at. My previous video about corrective morphs with an elbow generated a few questions about multi-axis and multi-joint corrective morphs.
The key is this: get your weighting correct first. If you try to sculpt on top of bad weighting, you will be fighting it constantly. Get as far as you can with weighting, and then go on to sculpting. Hope this helps!