It's a Choice really if you want to wash them, or not though.
I do incubate both washed, & unwashed eggs(Not at the same time), but that's just the way I roll.
I sterilize my incubator after first washing, & wash my hands before reaching in for any reason.
I did have a case of 5 chicks in my old incubator(Eggs were not washed) that died of Mushy Chick Disease. Fine eggs zero cracks.
Yolk sacks were green, & unabsorbed.