A while ago peple were saying the sweet fluids (for the fishing quest?) caused other quests drops not to drop.
I noticed that effect... initially. The coins drops went WAY down when the fishing quest was active. However, I tried it again last week, and got more coins than ever. So, my opinion is that the fishing quest messed things up intially, but it was quietly fixed.
I never noticed an effect on drops tho, only on the earning of other quest items.
Getting a single non-adena drop in two hours and sweet fluids from every mob had me a bit discouraged, but I finally got my book - and I ain't going back down there to check if it's better without the quest!
I don't know if its actually true or if I am just the unluckiest person in this game. Seems to me that the drop rate for full items and thier parts has gotten worse every chronicle. Haven't had a full item drop since lvl 38. I wanted to farm the blades for my SoV too but after almost 2 months of killing the same mobs I only got 4 blades. Of course that is only 1 or 2 hours a day but still at this rate it would have taken me six months to get 12 blades.