What day are they on? Sometimes if most of the egg (minus the air cell and a bit near it) is dark and you're near to hatching time, you are simply seeing the chick start to take up a lot of the space in the egg, which is completely normal.
Can you post a picture of the crooked air cell? Sometimes they are a saddle shape or they are detached, especially if the eggs were shipped to you in the mail. They also tend to develop a little crooked (not completely centered in the egg) no matter what. I can't tell for sure without seeing photos, however. I have no experience with saddle shaped or detached air cells either, as all my eggs have always been from my own chickens, but I believe I've read that they still have a chance at hatching like this.