Quest given out without proper faction
 

I don't know if you care about this kind of a bug..

This quest: http://wiki.project1999.org/Princess_Lenya

If you try to get the quest without enuf faction, you can't - BUT - if you use the wiki guide and skip to the line about being a veteran, you can get it anyway.

I saw this same quest in solved, but that issue was for getting the quest with faction.

There are quite a few quests which can still be completed despite the npc not 'trusting' you.

These seem to be a case by case basis. Only way to verify would be to find the npc on a running live server and see if it's possible.