Seems like someone posted this at the mmo-champion forums (
How to get guild to level 25 FAST!!)... and people started sending tickets.
According to a response posted there (2nd Page, Post #26), Blizzard seems to handle this as bug using - even though it is technically not a bug, but "broken by design":
"we have reported it to our developement team. If it is indeed found to be a bug, those who have exploited it will be punished accordingly."
So we should probably be careful with repeatable quests.