There's at least two examples of intelligent play in handling the last encounter.
Robilar (Rob Kuntz) fled after scooping up as much treasure as possible rather than fight the demi-lich (not sure if he touched it or not, I would guess not).
The tournament winning group that used the scepter and crown solution.
How is the first one actually intelligent behavior though? How would you know that this actually was a monster? Remember, this is 1976. You've got a skull full of honking big gems. You've already "defeated" the ghost that was guarding everything. What would tell you "Don't touch the skull"?
Now the scepter/crown thing? That's cool and creative. But, remember, you had to sacrifice at least one character (either PC or NPC) to get to that solution.