I've been leveling a Warlock recently. I haven't been rushing him, as I have several other characters I play regularly, but have been steady on him for about a week. I had been cruising along and everything was going really well. I got to 64 in Hellfire and headed to Nagrand. Almost instantly I felt like I didn't want to play that character anymore.
Over the course of the day I pondered my change of heart. I've enjoyed the class (as much as one can enjoy leveling with full enchanted heirlooms). I've found that I really like the troll animations (only other troll I've played was a feral druid). So, what happened?
I realized that I have six or seven other characters parked in Nagrand that I never touch... some for 5+ years.
I'm not 100% convinced that Nagrand is what kills my will to level, but something makes me give up on characters when they are going through that zone.
What zone is your alt graveyard?