we send in polyboxes and most of the time its ok, however if you candle and roll the egg, the whole insides turn, i think these eggs have been shaken too much.
but then there is the cheats from the other side, you send out eggs and constantly get emails saying fertility is good, then out of the blue someone kicks off saying none are fertile eggs are crap....what do you do??? We always replace if the buyer covers the postage, but it does make you wonder........
we incubate contantly through the season to check fertility, this at least lets you know if the cock bird is working