From what I have seen, the Yugos appear to have been well used prior to import. Some are pretty rough. The Chicoms are no longer imported but when they were, they were pretty much brand new. Any wear was experienced after import. The Ruskies are the originals and are sought after. Prices wil be higher on them.
I have a Chicom that I bought new about 15 years ago. I have fired about 1000 rounds through it with out any problems. Most ammo was US commercial, not corrosive Berdan steel case stuff.