Don't think you're supposed to wash eggs, even if they get muddy unless you're worried about toxins in the mud. If you wash them then you're wiping off the mud (which is harmless unless you think it's caked the entire egg and stopped air flow) but you're also wiping off anything healthy on the egg. The less tampering with the eggs the better, usually.
@ A. T.:These ones are under a broody, not the incubator. I would think it would be more of a hassle to take them from her, wash them, and try to give them back to her than to let them have a little dirt on them.
@ Kasey: I think they will still hatch. Are they out in the actual rain or is there just a muddy hen sitting on them? If they get too dirty, like you can't see white, you might want to rinse them off once the rain stops. If they're outside, next time you may want to look into a way to move the broodie to inside a coop with her nest.
i'm buying the hens from someone so not sure how they are but they said i could keep the eggs also so i'm just going to put it in the incubator bc i didnt figure she will still sit on them once there moved