I have looked at houses being renovated in my area and some are being done to a high standard and others you can see from the block and brick work that they are not really that good. However, what all is said and done, they will be plastered and decorated and no one will be the wiser about what lies underneath. Buyers will still pay the same or similar for the well-built and the poorly built one. Estate agents won't know which house is better built.
So in the end, it is probably not worth paying more for nicely done work that no one sees?