Hi, since the 2.3.0 patch; as you know dustwallow as been revamped with a series of quests I have recently done these on my new, upcoming main and found a rather intresting quest to exploit.
The exploit itself allows you to permanetly teleport to dustwallow marsh infinate times via a quest NPC in Stormwind.
The quest chain is alliance only and can be done by someone around the minimum level of 35, the chain starts off with this quest Quest:A Disturbing Development - WoWWiki - Your guide to the World of Warcraft and continues until you go to Stormwind and speak to the Stormwind Boss.
He will complete your quest and you have to go hand in at Jaina, DO NOT DO THIS, instead he hints that you can talk to a mage apprentice outside the mage quarter for a teleport, talk to him and he will open up the teleport... as many times as you like. Just don't hand the quest into Jaina or it won't work.