Nobody has mentioned the "bloom", which is the anti-microbial "lady juices" the hen's system coats the egg with before it exits the chute (regardless of "sharing" or "not sharing" that opening with fecal matter). Poop on the eggs most likely comes from the nest, which some hens just won't refrain from pooping in.
Poop on your chicken eggs has absolutely no impact whatsoever on the contamination inside the egg if you do not wash it. Rinse and wipe the surface and it becomes vulnerable to bacterial contamination through the pores opened by washing away the bloom. I've kept eggs, bloom on, on the kitchen counter for 3 months and eaten them as though they were fresh, no problem. A little dehydrated maybe, but no bacteria. My digestive system and I are here to tell about it.
Additional supporting evidence: gajillions of healthy chicks hatch every day from eggs that have never been washed.
Edited for grammatical clarification purposes