What glitch? Do the crime, do the time. Whatever. Strangely, however screwed up my toons have been, they always got through this quest one way or another. I think this is what they (Beth!) intended. It's just that they didn't anticipate all the crazy ways people would arrive at a particular quest juncture.
I've got an idea... maybe some quests, once acquired, should be pursued with great alacrity, rather than tossing them aside for later investigation. Maybe that's where the cookie crumbles and quests get buggy. We put them off long enough for so many possible influences to start to confuse matters.
Yes, it's the players' fault. Wonderful.
I have an idea, what about the smith in Markarth that you can't invest in? Will they fix her?
What about the permanent/hostile/invincible Unbound Dremora I have living in Winterhold?
What about all the other busted crapola?