Similarly, the 350/1s only show their age by the filthy carpets and threadbare seats. Nothing else is loose, rattly or damaged. They really are built to true German "premium car" quality. I bet in 30 more years they'll just look dated rather than knackered, a bit like some older BR DMUs and EMUs which are of similar quality - anything ADtranz or Bombardier built up to about 5 years ago will have fallen apart by then (though with the rounded-windowed *Stars they have really bucked their ideas up).
All they need is new seat foams, covers and carpets and they'll genuinely look new despite now being over 10 years old.
What SWR do need to do, though, is clean the ceiling conduits, they are truly filthy with 10 years of grime. LM manage to keep theirs clean, running a brush or vacuum along it is hardly difficult.