Ha ha ha.. your funny guy! No seriously you are.
My point being is that if your getting these rocks from a dry area then that's one thing,but if your going to get them from a pond,lake or otherwise wet area then their going to be dirty as hell with algea,dirt and who knows what hell else on them.
I've gotten my rocks from a pond that use to be rock quarry.So most of them where partialy submerged in the pond.The only way I could ever get all that crap off them was by bleaching them.
So...."overkill" I trhink not!