deerman beat me to it... clear eggs simply mean that they never started developing.
I have received eggs and had excellent hatch rates, and others where I get few or none. I understand the risk with shipped eggs. I tell the seller ahead of time (when I order the eggs) that I understand the risks and that I will let them know how it goes just for their information. If the eggs are in an auction, my feedback is based on communication, prompt shipping, and condition of the eggs on arrival.
eBay allows follow-up feedback, so if I have great development I place a follow-up to reflect that. With poor development I don't leave a follow-up and chalk it up to shipping.
I love it when the eggs are wrapped in bubble wrap and nested in shredded paper, though they can be a pain to open. Some of my least favorite methods: wrapped in bubble wrap and placed in an egg carton (I never have a lot of good results with those), in an egg carton with sawdust packed in the space around the eggs, and the peafowl eggs that I got this year were wrapped with newspaper with a piece of bubble wrap loosely wrapped around outside of the news paper and they were placed in with wadded up newspaper. I don't mind paying the shipping when there was obvious care packing the eggs, but I get mad when I pay that same amount to others and get eggs that aren't well packed.
Unless somebody is asking for a refund or replacement eggs, they may simply be letting you know how the hatch is going. If you feel that you should do something, I wouldn't do more than offer to replace the eggs if the buyer will pay the shipping and handling.