sorry to say this washing the egg reduces them to class b. you cant sell class b eggs to the public. if the egg is mucky try rubbing it off . if they are very dirty reserve for your own use. the odd bit of muck adds to the country freshness anyway.
If your flock is over 350 birds, and you are selling your eggs as graded eggs, then this is true.
On the other hand (or wing)
if you have a small flock of less than 350 birds, and
if you sell your eggs at the farm gate, door to door, or at a farmers market, then you can sell them as ungraded in which case washing is tolerated. You do not have to write "ungraded" on the box, you don't have to stamp the eggs. You must have a registered producer number, and your contact details, storage information and an explanation of the egg codes must be displayed at the point of sale. You cannot sell ungraded eggs in a shop, or to the restuarant trade.
On the other other hand(or wing)
if you have a very small flock of less than 50 birds, (and I suspect that covers quite a lot of people hereabouts) then the egg marketing board cannot see you as you are too small. You are thought of as a hobbyist, and you can sell your surplus eggs to friends, neighbours etc. You don't even need a producer number.