It looks to be about average for a "shooter" grade SKS Yugo from any of the major dealers out there, Classic, J&G, SOG, and the like. Obviously, the rifle was issued and used, but from what I can see, the stock is in fairly decent shape, though dinged up from field use and storage, and the bluing looks to be about 80% or so. The only real way to tell how much it has been "used" (by that I mean actually shot), is to take a close look at the bore. Are the lands and grooves in good shape or do they look well worn? Is there any sign of "fuzz" in the bore (very fine pitting, usually caused by the use of corrosive ammo and lack of proper cleaning after firing). The "proof of the pudding" so to speak will be when you take it to the range and see how it shoots. If the bore is not shot out, you should get very good accuracy from it out to 150 yards or so. These rifles are really, really fun to shoot, but you tend to go through ammo like it grows on trees.
So far as I am aware, Cpt., there is no way to tell for certain with these rifles if they were ever actually used in combat. The dealers buy them, usually rather cheaply in the case of the SKS, in huge lots after they have been declared "surplus" by their respective governments. Beware of anyone who tries to sell you any ex-military rifle at a high price by claiming it was "Hitler's personal weapon" or some such nonsense. Very rarely indeed is there any way to actually tell the specific history of a particular old military weapon.
For what it might be worth, Cpt., it looks to me like you potentially have a really great fun project on your hands if you like to restore old rifles. That stock, as I said earlier, looks to be in decent shape. Clean it up, sand it down, stain it, and apply a few coats of Tru Oil. You would be amazed at how good it will look afterward. You can touch up the worn bluing with any number of different products. My favorite is Brownell's Dichropan T-4, but Birchwood Casey and several others work nearly as well. Another option is to buy a synthetic stock for the rifle. ATI makes one and I believe there are several others who supply them as well. If you do that, however, you will need to get rid of the bayonet since most after-market stocks don't have slots for it. If you want to make the change permanent, you can entirely remove the lug the bayonet fits in with a Dremel tool and a little file work. The synthetic stocks make the rifle a great deal lighter, and I think, a lot more fun to shoot.