Opinions please!

Hiya, looking for opinions please! I sell my fertile eggs for incubating and I always ask for feedback. Quite a few of my customers say they’re not having the best success rate or having some quail with issues. I’ve done several batches hatching my eggs since February and I always have 80-90% success rate. I’ve stopped selling them because it’s just not nice to have the poor feedback and it just makes me feel bad, but I can’t see anything wrong with them or my quail. Any advice?