Your egg buyers wil never be able to tell the difference between fertilized and unfertilized eggs, except perhaps in their mind.
Yep, which is why I would NOT tell them! Most people have no idea what a bullseye looks like. Most people never think about whether the egg they are eating was fertile or not. But the ones who would freak out over it will only freak out if you bring it up. There is just no need to say anything.