Some of the pigment can be scratched off. It doesn't mean it's droppings. It may be difficult to tell feces and blood from speckles sometimes, but usually droppings have a different color brown (like a greenish brown) than the speckles. White streaks on colored eggs are urates, and part of the droppings. They should rinse off easily with minimal rubbing under running lukewarm water with a finger tip or damp paper towel. Blood would rinse off without scrubbing.
If your eggs appear clean, they probably are. Egg shells are porous, and scrubbing can actually "push" bacteria into the egg, so easy does it. I don't wash clean-looking eggs.
Edit for typos.