My pious Jewish mother always candled eggs she bought by the piece because she thought ones with red spots were fertilized, therefore equivalent to unkoshered meat.
Presumably this is the commented-on column.
I grew up on an egg farm. My father spent Tuesdays candling the eggs to be sold Wed. & Thur. I don’t believe you can tell a fertilized fresh egg by candling. Roosters are friers, and don’t hang out around the hen house. As said, the red is blood and not harmfull, though inappetizing.
I’m getting my eggs from a neighbor down the road from me. Red spots? Just ignore them myself. Probably get some of them fertilized, too, as she does have a rooster and the flock is very much free range during the day, hanging out in the yard eating bugs and whatever. Eggs is eggs. Also double-yolkers, smaller than usual, larger than usual… not nearly as uniform as what you get in the store but so much tastier!