She said "That's what a holster will do to a pistol. I see it all the time." I told her it was splattered like a chemical got on it. Holster wear is more even and shiny. I know what holster wear looks like. She said that was probably what the owner used to get the rust off.
Older leather holsters used a different method of tanning, and could cause rust if the gun was left in them. Especially if the holster got damp. Now, wearing the holster when it was damp would "pool" the moisture near the barrel end, even after you took the holster off. So, it's quite possible that was what she was talking about, but didn't explain it well enough for you to understand.
Part of the problem, of course, is that you're mixing generations. Things that were common knowledge to those growing up in the 50's and 60's aren't to the children of the 80's and 90's. Older guns, and accessories, from before then, are even more obscure today.
Most of the FFLs that inhabit the gun shows around here have a shop where they do most of their business. You CAN go see them on Monday. Prices are driven by more than the next table, too. many dealers have at least one employee helping them, and on the clock. The tables cost money, the more tables, the more money. Then, there's the fact, especially today, that a gun that was sitting in your inventory for the last four months cost you less than a gun that just came in. Quite a bit less. So, the EXACT same gun COULD be 25% higher, or more, simply because of when you bought it.
I don't ask for the "history" of a gun. I look at the weapon, and determine condition as much as possible, and will agree to a price, or offer what I think it's worth. The seller, be it an individual, or a dealer, can take it, or leave it. IF they ask what I found wrong, I'll be honest, and tell them. Both of us tend to leave in a civil manner that way.
If I don't know anything about the gun, I'll go out to my car, and look at my Blue Book. If you don't know enough to actually quote REAL prices, you have no business negotiating. Too many people decide what a gun is worth by looking at others, on other tables, the Internet, or, I swear, an Ouija Board, then, low-ball the dealer. After a couple of days of this, their being short is quite understandable. Half of what you get is what they've received already in banter.
I am a friend of Bill Ricca. He's a pretty well-known authority on older Ordnance Records, and tries to have a selection of 1903, M1 Garand, and M1 Carbine parts at shows that he attends. Spending an hour talking to him was enlightening. Part of the time was him giving other people information on the guns, and whether the parts that another vendor had were properly priced. Another part was in listening to "experts" blather on about how they "knew" where to find rare (mostly non-existent) parts, and how much cheaper they were than anything that he had. Then, we had those who saw a commercial 30 round M1 Carbine mag on another table, for $40.00, but his USGI mags were $100.00, and he was ripping off the customers. Sound familiar? A little knowledge is a dangerous thing. Especially when a key-board is close to hand.