That is something we have discovered since we started looking through CV a lot. It's bad. For houses that are less than 20 years old, they are in horrific condition. Noisy. Plastic pipes. Deteriorating walls. The list goes on.
I'm not sure if I agree with the statement about plastic pipes. First, plastic pipes have been used as early as the late 80ies in homes, depending on the applications. Provided the correct applications of PVC are used by the home builder, I would say PVC would probably hold up better than metal. I can't count how many folks I know who had to get metal pipes re-piped in due to pipe-hole leaks brought on from corrosion in metal pipes. The only issues I see is builders running these pipes in walls and a homeowner accidently hammers a nail or run a screw through a PVC pipe behind a wall, where he though it was a wood beam (yes, I've done that too. Not fun.)
If you look a several of the latest plumbing fixtures, most more plastic than metal these days. Not only cheaper to make, but supposedly more corrosion resistant.
