So I've been to the ghost farm, spoken to the slag, brought the message back to Jo, went back to the farm to find out that Karl ran away to the Northwest, figured out that he's actually in the Den, came back to him and I can't get any dialogue out of him that will further the quest.

What am I supposed to do? If I give him money or booze or ask about the GECK, he eventually passes out drunk. If I give him a nuka-cola, he spits it at me and passes out again.

Some walkthrough said that I'm supposed to "ask his story", but I don't have that dialogue option available. I remember I talked with this guy when I first came to the Den, and I do remember him talking about ghost farms. So does this mean I'm not getting this dialogue option now because I already spoke with him before? So my quest is now bugged and I can't finish it?

I found a possible solution - "he won't give you the story option, it's because you offended him by offering him Nuka-Cola or saying you'd give him money but then not doing it. Offering him Beer, Booze or $100 and then waiting until he wakes up again should restore the story line."

http://www.nma-fallout.com/showthread.php?157745-Karl&p=3239711&viewfull=1#post3239711

Oh wow, that worked! Thanks so much :) Your google-fu is far superior to mine :D

That quest causes confusion for lots of people. It can seem like it's at a dead end when it's really not.