Yup. Starcross was similar; I meant clues rather than copy-protection under another name. I played store-bought versions of these game (on my old Commodore 64) and never bought "invisiclues" so the line between these categories was quite clear. I don't recall what the medium of my final "tap out" in Zork 3 was - but recall being stuck for months and finally looking up the "hello sailor" bit.
This might not have been such a problem if I had played the Zorks in order, but I bought Zork 3 before Zork 1 because that was what they had in the shop. Otherwise I might have seen the verse in Zork 1:
"Oh ye who go about saying unto each, "Hello sailor",
Dost thou know the magnitude of thy sin before the gods?"