Well ignoring those ultra-expensive suites, the only time we have ever seen this was on an older ship, where we found that the dressing table was hinged & were surprised to find that it concealed a small sink.
We can't recall if it was on fred.Olsen's Balck Watch or Cunard's Caronia.
Alan & Katrina
Last: Cunard Queen Victoria January 2016
Next: Oceania Marina June 2016
Then: P&O Oriana August 2016
Then: P&O Oceana December 2016
Golden, Grand(2), Caribbean, Royal, Sea(4+1 aborted)
Adonia(4+2), Arcadia, Artemis(2), Aurora(5), Azura(2), Britannia, Oceana(3), Oriana(12), Ventura(2), Victoria(5)
QM2(2), QE2(9), QV(7), QE, Caronia(2), Minerva, Minerva II, Fred.Olsen(8), NCL Jade, =X= Eclipse, HAL Ryndam, Aza.Journey