I have leveled Bloodsail rep to get the hat during Burning Crusade and subsequently destroying the rep again via cloth hand in's just after so I could level cooking. Since then I have also done the Dire Maul grind for exalted goblin factions for my 40 exalted title (my favourite at the moment).
I don't think I could level Bloodsail from 0/36000 and then redo goblins a 2nd time. The Shen'dralar, Darkmoon Faire and Ravenholdt rep would be ok but not all of it together... I hope I don't give in to myself and try it.