You will read just about everywhere that you should not clean the eggs as it can force bugs through the shell. However, on muddy days if your hens are outside this means most eggs will be marked with some muck and in theory you will have to sell them mucky - but I doubt if anyone would want them.
Eggs for our own use I do clean with warm water - have been doing this for several years with no harmful effects on us.
If you date stamp the eggs on the day they are laid its much easier to keep track of how fresh they are (my customers really appreciate this) - but its not compulsory.