I agree with Mykeal that you should make sure the bore and cylinders are clean before sending it back. No offense to your cleaning abilities but it is hard to know what you are seeing without pictures.
I have been burned a few times with auction purchased guns but mostly they have been good experiences. I have learned to ask very specific questions to the seller about the guns condition. At least you will know what the gun looks like in pictures, which can be deceiving. I remember a situation where I was bidding on a stainless steel gun but some of the pictures looked like there was rust on the gun. The seller assured me that what I was seeing was only a result of lighting and that the gun was not rusted. I took him on his word, and sure enough the gun was fine. Point is that pictures can look better or worse than the actual condition of the piece.
Ask as many questions as you need, most sellers are happy to oblige you, if they are not, you should look elsewhere.
Do you have any pictures of you 1860 that you can post?