Chickielady - thank you so much for the information. I haven't seen any of these resources - they will be very helpful.
Blood spots on the yolk are called "egg meats" and are caused by minute ruptures in the ovary when the yolk emerges.
Big egg farms candle eggs to remove any eggs with "egg meats" so you seldom see a commercially farmed egg with egg meats.
Washing eggs does not do anything to stop embryo growth, temperature does.
An embryo will begin to grow before the egg emerges from the warm confines of the hen's body, but will halt growth as long as held below 55 degrees.
Hatching eggs do not get washed as washing removes the protective coating called a "bloom" that covers the egg & seals out bacteria.
Washing eating eggs is necessary...following USDA directions, use 120 degree water in 2 containers, add a spray of bleach SOLUTION or a tiny bit of auto dish washer detergent to each....measure temp with a stem (meat) thermometer so water is at 120 degrees.
Put eggs in 1st bowl & use a seperate sponge to gently wash each & place in 2nd (rinse) water...leave in the water 30 seconds...then remove to a colander to dry.
Then paper towel to dry & into a clean egg carton and into the refrigerator.
Small bits of poo can fall off unwashed eggs and get into the food...and it can make you or others sick.
If you sell eggs you need to wash them just in case someone does get sick....cover your behind !
I can look up the USDA link & post it for you.
This is a cool pdf...I cannot get my puter to open it right now but here is the link:
http://agr.wa.gov/marketing/smallfarm/DOCS/056-SmallFarmAndDirectMarketingHandbook-Complete.pdf
I will keep looking for the egg washing page
here is the egg washing (one of many) articles:
http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=798
http://agr.wa.gov/marketing/smallfarm/savorWA.aspx
Click the link on the left that says "Small Farm Marketing Handbook" and see loads more info !