I tried a Half-Ogre with only 4 INT, and there's no way that I can beat the game without using INT potions.... which is weird, because the INT is only needed to initiate the conversation, not to continue it (ie, with Nasrudin)
There are a few known bugs in the dumb dialog routines. Naz is one. Fan made patches are available here & there. One poster on the offical VU Arcanum froum, Da real Asrudin (spelling?) has come up with a comprenhensive bugfix pack. While it mostly fixes gear, like the Amulet of Scilence & the Caladon Cruasding Armor, I believe dialog bugs were fixed as well.
You apparently refer to INT on the mainline quests. But if you mean other quests, too, then I recall a strange little quest from the Mayor of Ashbury, hosting a town meeting. The right responses that will let you gain maximum experience from this "quest" require a decent INT. I know that my Elven Pure Mage with an INT of 10 required an INT potion to respond properly.
The funny thing about that quest with my INt 4 Half-Ogre... I walked in during the meeting, realized my half-ogre is too stupid to do anything, and left... then after wandering around and doing some sidequests ("Liam's portal"), I came back and somehow completed the quest which I never received....
Odd. (That anonymous post, above, was mine, btw. Somehow, my cookie crumbled.) I tried the meeting first with an INT 10, and still lacked the last couple of "right" replies. It was only after reloading and downing an INT potion that I was able to probably complete the quest.
In 12 is what you need for all the right answers, but going higher will prune some bad choices. Enough CH, I have been told, will get them to cheer all but the worst ones. Balint, someone else reported the dumb dialog auto cheat on another site. As I am finaly running a Supermodel all the way through as dumb, I'll try that one out soon. Did you talk to the Mayor?
Not when I was playing that section. I patched the wrong drive so I thought I patched it but I didn't... strange that with a game that's not THAT old, it doesn't have a decent setup program for a patch. At least it should read the registry for the location of the game instead of asking you to find it, AND have it not check if it actually is a game directory...