Why, when you try to edit an dummy npc, do they all seem to take off walking to the east? They aren't even walking, they are sliding off to the east.
If you change the skin while the NPC is walking, the animation resets until the NPC stops. We will fix this cosmetic issue with the next update
However, if you don't want the NPC to walk around (which happens randomly) while changing the appearance, I'd recommend to lock it first by typing "locknpc 1", and once you're ready, it can be "unlocked" by typing "locknpc 0"