Credit to both Metropolis and Nonesuch for not only responding to my emails, but promptly and uncomplainingly sending replacement copies of the Gary Numan and Stephin Merritt albums. Double credit to Metropolis for not minding that I had abused my first copy of Jagged fairly badly, trying out various supposed copy-protection circumvention techniques. Double credit to Nonesuch for not minding that I had returned my two copies of Showtunes, and they were thus sending me not so much a replacement as a free copy for my trouble.  

Of course, both new CDs have exactly the same problem as the old CDs. They're defective pressings, not defective individual discs. Triple demerits to both labels for not having figured this out by now. Or for not admitting having figured it out, if in fact they have.