I don't honestly think there are any "bad" clerics in game, i think at times people get annoyed with the fact they ain't getting healed but there is always priority heals for example the tank.
Some clerics amaze me, healing whole party in abyss while everyone tank mobs
its pretty skillful i don't think i could do it. Other times you do get a cruddy one that just fails...
My mate is a cleric and i find it very easy to grind in a duo with him and will continue to do so
Being a fighter i don't need the duo all the time but its worth it at the end of the day, esp for archers/mages.