I feel you. I main on bard and me and my tank buddy dread the times when there is another bard in the same run. Well...at least it makes it pretty predictable whom to watch out for because in 80 % of all cases this second bard will pull hate. My buddy is a pretty good tank and well geared but all of that doesn't help if the bard is attacking too early. The existence of quelling strikes also seems to be unknown to some of them.
When I pug, I try to gauge the tanks ability with the first few pulls. I generally wait a bit in the beginning and then start my rotation...if that is still too much I start each pull with quelling strike activated to give the tank some chance.
I all that doesn't help...well...then I have to auto attack through the dungeon and the problem is somewhere else.
Personally I think that most hate issues come from trigger happy brd and blm that can't wait a few seconds for the tank to grab hate. That and ignorance towards hate reducing skills because it might lower their dps output or something.