I was being inaccurate also, I just wash off the eggs anyways because I don't want the chick to have to break through poop or pick at it when they have hatched. I also had issues with a person who gave me 2 clean (with poop smudges) & the rest poopy eggs and none of them hatched. One even exploded under the broody it seemed. But the eggs could have stopped developing, we did candle them and we saw a development, so we let them be, but bad luck.. I wash my eggs with bleach, then vinegar, during selling, but not when hatching, just a warm washcloth.
I would not worm or treat for coccidia when collecting fertile eggs. My rooster who hatched from a egg that was collected during I think worming time, he's bit brain damaged it seems... he talks more than other chickens, and takes time to process that there's food in front of him...