Well I really don't see a problem with accuracy in the SKS rifles I have shot,even one's that I don't own and have shot that belong to friends. Other than the condition of the rifle and bore the ammo you put in them has a lot to do with there accuracy,to me there just another rifle you have to tune your ammo to if you hand load to get the best from them.
The only modification I have made to the original rifles is replacing the front sight pin with a Techsight target post,cost me $12 for two shipped to the door. I'm a firm believer when shooting iron sight that if you aim small you shoot small. As far as a blank statement that any SKS is inaccurate,I would have to see the rifle in question,ammo being used in it and the ability of the person firing it. Just throwing lead downrange with the cheapest ammo of the day and never adjusting the sights properly it's no wounder you see so many claims of the SKS being inaccurate.
My two SKS rifles are just as prized to me as my Sav. 99 in 300 Sav. I just don't see them a a cheap 30 cal. plinker or truck gun. My Chinese shoots pretty much the same as my Yugo I can interchange loads between the two with no real noticeable affects other than POI,the Chinese tends to shot a bit lower with heavier bullets than the Yugo and slightly to the left with identical load fired in the Yugo but thats not a big deal once you get use to it's characteristics with various hand loads. Here are my first test load one in 123 gr. SP and FMJ hand loaded and my most recent 5 shot group test loads using the identical cast bullet load I shot in the Yugo. The cast bullet load fired in the Chinese was for accuracy test only and not for POI,I shoot all my test groups at 50 yds. because that all the room I have in the back yard.