WoW TBC: Gold Farm, Infinite Mob Spawn From Quest Item (NERF) (Patreon)

EDIT: When I tested this item it didn't seem to have a cooldown (something borne out by older sources mentioning this farm), but according to reports from patreons it seems to have one now even if it didn't before. It still has some value as a means of maintaining mob density whilst farming mobs in the area.

The Level 61 Zangarmarsh quest "Balance Must Be Preserved", 

https://tbc.wowhead.com/quest=9720/balance-must-be-preserved

gives you the quest item "Ironvine Seeds"-which are attached to one of four steam pumps destroying them in the process. 

When you attach the seeds to the pump a "Steam Pump Overseer" materializes and utters some dialogue. You can spawn and kill endless overseers with the quest item, the only requirement is that the preceding overseer must be dead before a new one spawns. 

The overseers do not award experience*. However, they do have a normal loot table.

 In particular they drop unidentified plant parts, which can be sold on the ah or turned in for Cenarion reputation. 

They also drop jaggal clams which have a chance to contain jaggal or shadow pearls-the value of these can be enhanced by jewelcrafters (the auction houses I looked at suggested the player base does not know what these are worth-they are often selling significantly below vendor price). 

There is no way for solo players to farm these items as efficiently as with this glitch farm.

I have received a number of queries from people on youtube and here on patreon recently who wanted to know why instant re-spawns were advantageous. The reason is this: there is no downtime moving between mobs. You kill things faster. The faster you kill things, the more gold you make. If all drops were the same (and in wow classic this is more true I think than people perceive) mobs which instantly re-spawn would produce the most profit.

*(While the spammable mobs do not award experience it is worth mentioning the overseers drop 3 different items useable for quests.)