My crested/blue Swedish cross is usually pretty clean, at least with her eggs. My silver Appleyard was a giant hog and made sure to lay her eggs in all of the worst places (in the water dish, in the food dish, in the biggest pile of poo they had in their house...) then I gave her an old EOS lip gloss container (didn’t have any fake eggs haha) in the corner nest box and she’s been laying beautiful clean eggs in there ever since. I had tried one of her other eggs in there and she tossed it out and laid the next one in poo.

she seems to have gotten it figured out now, though.
If we’re talking cleanliness in general though, both of my girls are filthy in the mud puddles in the yard. Then they come back to their kiddie pool or the water tubs and wash it off.
on another note, I have development in every egg I’ve checked from my 2 batches of eggs!