what I am seeing is insulation, studs, then the vapor barrier is stapled to the studs over the insulation then the drywall is put on, I am mainly dealing with this on painted walls, the problem I have is when you add water to the sheet rock it makes the vapor barrier wanna cling to the sheetrock, which precludes getting any air between the sheet rock and the plastic, in this case where the water has came from above and ran down the wall, IMO I think its pretty tuff to save the wall, what I have been doing on a typical job where the wall is only wet maybe a foot up is, pulling base and pocking holes through the sheet rock through the plastic so the air can get to the insulation behind then the wall normally drys ok with the bottom exposed where the base was