I have received some clean eggs that I suspect were washed before. If they are dirty I would rather wash them myself before setting.
That's one thing I never do is wash hatching eggs! I will scrubby dry mud spots off of them but that's all. If they're extremely muddy and I don't have clean ones available to fill the order, I ask the buyer if they want muddy eggs with LOTS of extras, or do they want to wait.
Although as a general rule, I don't even try to sell the muddy ones. I have stock pots I use for boiling them to feed back to the chickens.