If I'm selling eggs to consumers I feel an obligation to use eggs that were refrigerated within 24 hours of being laid. However, I am much less stringent with eggs for personal use.
The reality is that eggs are incredibly well packaged if the the hen is healthy and the shell is undisturbed. As an egg is laid it is covered by a protective sealant, which is called the bloom. The bloom seals the pores of the shell to prevent bacteria from getting inside. If you wash the egg, you wash off the bloom, and the egg becomes more vulnerable to spoilage. If you don't wash the egg, it is protected for a very long time, regardless of temperature. I collect many eggs for hatching. I store them up to two weeks at 50-60 degrees (for those of you considering this, fertility starts to decrease on day 7, so 2 weeks is a maximum, not a recommendation). That temperature is high enough to prevent the embryo from dying, but not high enough to allow it to start developing. Then they are put in the incubator at 99 degrees. If they don't develop I always open them to see what happened. I have never had one that was rotten or smelled bad, even if I left it in the incubator until day 18, at 99 degrees, after storing at 50-60 degrees for up to 2 weeks. So the bloom is very effective, as long as you don't wash it off.
I currently have some Dorking, Langshan, and Speckled Sussex eggs in my refrigerator that were laid in April 2014 --10 months ago. (I date stamp my eggs when they are collected, so yes, I'm sure of the date.) They are fine to eat, although I do break them one at a time into a separate bowl before putting them into the frying pan or mixing bowl, just in case. My hens are free range and healthy. I know their favorite nesting spots, and keep clean bedding in the nests. I collect them daily, and do not wash them. If they are intended for consumption (instead of hatching), I store them in solid cardboard egg cartons (not the vented ones that are so popular now) in the refrigerator. Typically, they show no signs of albumin dehydration with this method of storage for 4-6 months. At 10 months old with this method of storage, the albumin has some mild to moderate dehydration, the egg has typically lost 9-10% of it's weight, the yolk membrane occasionally sticks to the inner shell membrane since the egg has not been turned daily, and there is more thin albumin and less thick albumin than with a fresher egg. But they're not spoiled and they taste fine. I really think the solid cardboard is the secret to such long storage times, as the refrigerator cannot dehydrate them as easily.
This timeline will not be true for all eggs. Different breeds and different individuals will have different shell porosities, and different bloom qualities. I have one Buckeye hen that lays an egg that looks absolutely perfect, but only lasts 4-5 months. Before month 6 her eggs will start to rot, no matter how they are handled and stored, so I suspect she probably produces an inferior bloom. I have a Dorking hen who lays a terrible looking egg, but it will consistently store for 8-10 months despite having an almost incompetent shell. Her bloom must be amazing!!
I never considered counter storage (as opposed to refrigerator storage) until a friend of mine asked me how she should store some eggs I had given her. I didn't understand the question -- doesn't everyone store their eggs in the refrigerator?? She explained that her Southern grandmother only stored "those icky store-bought eggs" in the refrigerator, but she always stored her free range farm eggs in the pantry. She said that they only had 3 hens, so they rarely had farm eggs that weren't used within the week, but that sometimes friends would give them eggs and they had been stored in the pantry for as long as a month without concern. I was surprised, but then thought about my hatching eggs. Those blooms have to protect an embryo for up to 2 weeks before development, then 3 weeks of development, without allowing any infection to penetrate into the shell. Of course the bloom can keep the eggs from spoiling at room temperature for a month -- if they couldn't, there'd be no chicks hatched. We just have to leave the bloom alone and not wash it off. It's amazing the things that Southern grandmothers know.
Another thing to consider -- there is probably a huge difference between the eggs of free range, healthy hens and the eggs of factory farmed, battery cage hens, which are miles away from healthy. Salmonella is a common problem in battery cage hens. Salmonella is usually an intestinal infection, but a stressed hen can have the infection spread to her ovary. The ovarian infection gets into the developing egg yolk, and is therefore inside the egg before the shell is formed around it. The bloom can't protect against contamination that is already inside the egg before the shell is formed. Therefore, counter storage of those eggs is probably not safe, as the higher temperatures outside the refrigerator allows the Salmonella infection to grow, which could possibly make someone sick if the egg wasn't cooked thoroughly. Salmonella infection of the ovary, and thus the egg yolk, is extremely rare in free range hens, so counter storage of those eggs is much safer.
The Salmonella issue could also explain the 45 day limit, as even refrigerated bacteria will eventually grow, just very slowly.
