I naturally distrust any ebay listings that have associated paperwork. That's not to say some are not legit, however. It's just far too easy to fake these....much easier than faking black paint! And relatively few people know what original paperwork really looked like 50+ years ago...unlike telltale details on fake cameras. There is lots of information on the net on how to spot fake cameras; how many web pages show people how to spot fake papers?
There is one seller there who routinely has 'matching' paperwork for every Leica listing he sells. He's not hard to find if you look.
I've been watching him for over five years now...there is absolutely NO WAY that a seller can keep acquiring that many items with matching paperwork for that long a time period. Impossible.
Matching paperwork results in highly inflated final auction prices. Mundane Leica pieces, none particularly rare although all in excellent condition, will get thousands of dollars additional because of the matching paperwork and boxes. A $1,000 M3 might get $3,000 for example...not a bad return for maybe $50 of expense acquiring empty boxes and reprinting papers...
I know this for absolute fact as he has bought items from me that came with no matching serial number boxes or paperwork, and then resold them at a later date, this time magically appearing with 'original' paperwork and 'original' boxes with 'matching serial numbers.'
I have reported him to ebay several times. I did all the research for them.
I provided ebay with links to listings of:
(a) product boxes that he purchased (proven, via feedback, they were bought by him)
(b) lenses that he purchased from me
and the listings where he resold the very same lenses (confirmed via serial numbers in the photos) together with recreated paperwork with matching serial numbers, along with matching serial numbers on the so-called 'original' boxes.
He's been suspended off and on by ebay, but keeps reappearing. He's broken so many ebay rules its ridiculous, he's even given himself feedback between multiple accounts that he operates.