It's a long read, but I believe relevant,

Needless to say, that party in particular lost 2 important NPCs with the PC monk blinded by Glitterdust and knowingly running through a Spirit Wall after already being hit once and gaining a negative level.

He now lies unconscious and with 2 negative levels past the wall and alone, since the rest of the party decided at around round 14 to flee (mind you that the Necromancer in question popped up at round 3 and had been spell slinging every round- these guys just took it and never opted to escape or, in the beguiler's case, dispel the guy so as to make him an easier target).

So is it good to punish PCs? It depends: If you hand out the info and tools beforehand and they choose to ignore them, then the gloves come off and all you can do as a DM is hope that they use common sense to retreat.