Here is a link to a thread on the Larian Studios forum which list known quest breakers and bugs for DD.
Many of these may have been fixed by patches since they were posted.
Hope it helps with the ones that were not patched out . . .=)

bump for sticky

Nicely done. This answers my question about George's quest from my other post (I stole the herb in the beginning of the game, breaking the quest) and will help me avoid future troubles.

I forgot about the herb theft affecting the quest . . . DD gets fairly involved with some interesting quests. Glad it helped, I try to bump some of the more helpful threads but I get slack sometimes . . . =)
I am about to go to the wastelands on my second play through. I have enjoyed it more the second time since I have used magic much more and avoided some of the quest breakers. I only have one, the exquisite wine, I took the bottle from the room before talking to the wine merchant. It still worked for the summoning quest but I have that one failed quest in my log.