It is not just the dirt, now true if the dirt contains Poo-ish substances it will also harbor germy bacteria and or viruses, as we all know all living creatures are shedding viruses in their droppings, dander and so forth.
I was extremely reluctant to dip my eggs into bleach the first time. Bleach kills things! I was assured by the vets it would help and not hurt.
Here is the guide to NPIP practices, they discuss sanitizing eggs.
https://www.poultryimprovement.org/documents/ProgramStandardsAugust2014.pdf
I have to be honest I have never felt like unleashing the plague of this world by hatching DUX. But is some ways DUX resemble birds. Eggs is one way.
I have an egg which is severely cracked incubating right now. I did put "nuskin" on it after I had washed and disinfected it. I doubt it would be alive if my incubator and all the things in it were not sterile.
I open my incubator the other day, and I got the clean smell from the incubator. It was pleasant. I remember before I disinfected how had they could smell.
The eggs are really sensitive to substances during hatching. They are the embryos lungs. We worry about the moisture because too high and the birds drown, too low they dry out and the air sac crowds them. Does it not stand to reason moisture can get through the shell (in and out) other things can too?
I know my hatch rates went up once I started washing eggs. If I was pickier about the eggs I try to hatch it would be higher yet.
If I could find a NPIP source for DUX eggs, I would like to try them, just to see what I can learn from them. Of course I would cull and eat the hatchlings on day one. I could not live with myself if I left a DUX to harm my offspring and their offsprings......
