One of the first things I look at on a gun claimed to be new or like new is the the breechface. Depending on the finish, you may get several hundred rounds through it before the finish is worn off. I figured it was about 300+ for a Wilson Combat's Armor Tuff finish, for example, but you could see it wearning long before.
I purchased a 1974/6 rifle that was somewhat beat up, but the bore looked fine and the bolt face was totally blued except for a light ring of the cartridge base. Inside of 30 shots, the bluing was gone, LOL. So old gun, carried in a truck for years, but shot only a few times.
Anyway, look for all the handling marks. An old new gun (unsold for years, for example) can have lots of handling damage, mars, nicks, small scratches, irregular finish due to hand oils not wiped away etc.
"If you look through your scope and see your shoe, aim higher."
-- said to me by my 11 year old daughter before going out for hogs 8/13/2011