If i asked you question about your computer serial number or say motherboard type or something similar that you might be fairly knowlegeable but not nerdy about, could you provide the information someone asked for? if not does it make it ropey or stolen? No it means the person does not know how to find or aquire the information you require.
Again reciepts are easy lost and not every one even know what bike shepard is.
I can most certainly tell you the serial numbers of my computer systems, how much ram they have the speed of the ram, the make and serial number of the mobo, the OS version and the ROM firmwear for my Android Tablet and Phone but then again I am really nerdy so its probably not a good example.
The fact remains that all bikes come with serial numbers, and although I may now appear slightly obsessive and weird even if the owner does not know where to locate it, you should find out where it is located. The bike manufacturer can provide this information.
I would then advise checking the serial number with a dealer, in most cases I am aware of the dealer is usually quite happy to call the person the bike was sold to just to confirm if they sold the bike should the name not be the same as the person you are dealing with.
If the frame number or proof or purchase can not be located, I would suggest walking away, If you buy stolen goods and the person who they were taken from is identified they will be returned and you will be out of pocket
It seems strange to me not to have this information at hand and a little suspect but then again that's just how I perceive things, never ever conceived that my behaviour is a little different from the norm
