Fresh chicken eggs are da bomb. The egg whites cohere and do not spread out in a puddle. You might be buying organic eggs (or free range, or wot-evs) but if the whites are runny and spread out in the pan, the eggs are NOT fresh.
Hoping to get a coop up later this year and start experimenting!
The whites don't separate from the shell well if they're too fresh
Age is definitely one big factor. The longer they sit the lighter they get. But I suspect diet also plays a big role, and to a lesser extent, lifestyle/overall health