Wayne,
About the only way to buy an ‘as made’ gun, is to buy an inexpensive one (relatively speaking). I’ve seen lot’s of completely original rifles, but they were all in the $2000/3000 price range.
So for your question I’ll assume you’re talking about guns that have at least a decent degree of value. And naturally the more expensive the rifle, the more work it is likely to have had, assuming it needs work.
Restoration, for and against, has been hashed and bashed about here a couple of times, with no real consensus other than some guys are for it, some against, and seemingly never the twain shall meet.
So for your question, I’ll pick an imaginary rifle worth about $20,000/25,000.
If the barrel has been shortened, it’s been restored to full length along with the forearm wood.
If changed to percussion, it’s been reconverted back to flint.
If its missing wood at the toe of the stock, between the lock and tang, or sizeable splinters knocked out of the forearm, etc, they’ve all been repaired.
If it’s missing some original inlays, they’ve been replaced.
And if the lock, or trigger guard has been lost, they’ve been replaced too.
But, if the finish is a bit tattered, it hasn’t been stripped and refinished, but instead just some concoction rubbed into the wood to help return it to a degree of life.
And I’d say my imaginary gun isn’t unusual, because I’d guess that about 95% of guns in this price range have had whatever needs fixing, fixed.
On your flip-side question, I’ve seen only a couple of pristine guns in my imaginary guns price range, but being pristine, they are now priced at $30/35K, or more. For those wanting to see an example of what looks like a very pristine rifle, see the latest Beyer posted in the Library section.
I too agree that honest restoration is a worthwhile endeavor. And while I respect the purest view that nothing should be done to an old beat up gun because that's its history and lot in life, fact of the matter is that most guys buying pricy guns expect a gun that looks the part, and not something held together with bailing wire, tape or rubber bands.
However that’s not to say that same guy finding a good gun needing work won’t buy it. Because he will. At a discounted price. Then have it restored!
A quick look in the books shows very few beat up rifles. Believe me, those in nice condition didn't all come down through time in that condition!
If this topic catches you’ll likely get some good answers, so I’ll get a bag of popcorn.
John