questions on candling results

After looking at candling pics on Metzer Farms page, I had questions about the viability of our eggs at school.
I checked them all again today. Of 21, I'm sure 14 are good (and all 4 chicken eggs). The other 7 seem similar to each other, but not entirely similar to the 14 good eggs, though some are closer than others.







Craptastic image, but you can see how there is more "stuff in these ones and less veining. Most of the Iffy 7 are like this. But there are still easy to see veins.

Another questionable one - veins and 'stuff' but no clue if it is a good egg or not



Even more craptastic image, but one or two look like this - if you look hard with turning the egg the right way, you can see veins no problem, but lots of 'stuff' in there.



bantam chicken egg




All the easy to identify good eggs were moving around like crazy. I dragged teachers and directors into bathrooms and closets to show everybody LOL
The "iffy" eggs - some seemed to maybe move.

Duck eggs were set on 28 March and due to hatch ~25 April. So they are day ~19. The chicken eggs were set a week later and also due to hatch ~25 April.
The "iffy" eggs were most difficult to get pics of since there isn't a lot lit up.
They ALL have air sacs at the fat end on top.
Any insight?