When laid, an egg is coated with a protective coating called “bloom” which dries on the shell and seals it. The bloom helps protect the egg and keep it fresh by blocking gasses and bacteria from passing through the porous egg shell. Eggs also get other material on them from the hen’s feet, or the bedding they’re laid in. Commercial eggs are washed so as to remove anything on the shell, including the bloom. This is another reason for the difference in freshness between commercially produced eggs and home produced eggs.
Some commercial egg producers will apply a light coating of mineral oil to the eggs after washing. This serves the same purpose as the bloom, but doesn’t dry the same and may not provide quite the same level of protection.
Because of the benefits of leaving the bloom on the egg, we don’t wash our eggs prior to selling them unless a buyer requests that their eggs be washed. While we will brush the egg, or pick off any foreign matter as best as can be done without washing, we do recommend that eggs be rinsed off before use. Regardless of where your eggs come from, also take care to crack the egg in a manner that brings the outside of the shell into as little contact as possible with the interior.