Yeah, it's pretty nasty, I counted it up, and the one lone black pudding made 22 touch attacks in two rounds of combat, without landing a single actual melee hit. That was just on me, I don't know how many it threw out on the others in that time.
22? I am not sure how that could possibly work in two rounds, absent a glitch in the script somewhere. I have been in those mines and not had that much trouble, honestly -- but then again, my characters generally do not wear metal armor nor do I use metal weapons when confronting them (puddin' mashers rule!). The only thing I can think of is that the pudding is making one touch attack on you, but it targets each metal item you carry separately to see if it is affected -- i.e. the fewer metal items you carry, the fewer touch attacks will be registered in your log. Touch attacks are controlled entirely by script, as I understand it, and do not follow the normal NWN combat engine, so it would not matter whether it registers as a melee hit.
Thus, I am guessing (and again, this is just speculation on how the script works), if you were carrying metal (1) armor, (2) helm, (3) shield, (4) sword, and (5) boots, the pudding might attack you once, but register 5 touch attacks -- one for each of your metal items.
If this is the case, then confronting puddings is not merely an exercise in a muscle-bound sword swinger chopping them down -- it requires strategic thinking, and retreat if necessary. My rogues with their slings and puddin' mashers (and some haste) never really had horrible problems with them (did get a helmet damaged once, but that was the only metal object I was wearing at the time).
Rings and amulets ought to be interesting -- not all metals react in acid. Copper, silver, and gold, for example, are very unreactive regarding acids (although copper and silver do react with oxygen -- creating verdigris and tarnish, respectively).