So I join Haukke Manor today as a Whm and spent the first few minutes of the run being told how to play by a tank who was just this side of living in a home. I got agro on every single pull... often on his 1 mark.
So after the first boss he magic D/cs and we stand around for awhile before I got bored and decided to start pulling. Arc, Drg, Whm and we cleared from the first boss to the last boss (yes we downed the second boss with no tank) with no issues... no deaths even.
Last boss I knew we couldn't do without a tank but tried anyway and failed. So I dropped, changed to paladin and queued up and got back into the group. A healer joined a few seconds later and we took out the boss.
For an added bonus tank gear dropped in the instance... a lot of it.
Tl;dr Bad tanks are bad... and in many cases not even needed.