Over the past few years, I've been buying (mostly though e-bay) old AD&D and Basic D&D products that I missed back in the day... which is to say, most of them. 
Sitting in front of me at present is a 2nd-hand copy of the AD&D Player Character Record Sheets and one of the Dungeon Masters [sic] Adventure Log. Both have been slightly used, and it's interesting to look at the scribblings of D&D players from - I presume - many years ago.
Only one character sheet was used - for Kendrick Fyn, a level 1 Human Ranger. Str 13, Int 14, Wis 16, Dex 12, Con 14, Cha 17. AC 4, hp 13. The character was made for a World of Greyhawk campaign in 575 CY. Interestingly, the background of the character is filled in - apparently by the DM.
"Abandoned in the Suss Forest as an infant, you learned the ways of the forest as you grew older. Your only friends were animals and birds until Astria, a kindly ranger adopted and educated you. You haven't had much contact with the outside world, and don't really understand the customs and prejudices of the human race. You harbour good will to all living things and help out where needed."
For all of that, there's no indication that the character was ever played - or, at least, the details of the adventure have never made themselves shown on the character sheet.
Meanwhile, the DM Log, although most of the pencil writing has been erased, it's still mostly legible.
On one occasion, the PC Firestone (NG Human Fighter 4) and his three NPC companions Striker (LN Human Fighter 1), Death (NE Human Fighter 1) and Hearty (NG Cleric 2) faced a number of opponents...
A Gnoll
Ogeres [sic]
10 orcs
Ratty the Lizardman
Teeth the Lizardman
Death the Lizardman, and
Strong the Orc
From that expedition, 150 GP was accrued.
Another expedition seems to indicate the PC was joined by a Manticore, Otyugh and a 8-headed Hydra, but I may be misinterpreting what the book was being used for by this point.
If you've bought second-hand D&D products, have you found similar legacies in the books?
Cheers!

Sitting in front of me at present is a 2nd-hand copy of the AD&D Player Character Record Sheets and one of the Dungeon Masters [sic] Adventure Log. Both have been slightly used, and it's interesting to look at the scribblings of D&D players from - I presume - many years ago.
Only one character sheet was used - for Kendrick Fyn, a level 1 Human Ranger. Str 13, Int 14, Wis 16, Dex 12, Con 14, Cha 17. AC 4, hp 13. The character was made for a World of Greyhawk campaign in 575 CY. Interestingly, the background of the character is filled in - apparently by the DM.
"Abandoned in the Suss Forest as an infant, you learned the ways of the forest as you grew older. Your only friends were animals and birds until Astria, a kindly ranger adopted and educated you. You haven't had much contact with the outside world, and don't really understand the customs and prejudices of the human race. You harbour good will to all living things and help out where needed."
For all of that, there's no indication that the character was ever played - or, at least, the details of the adventure have never made themselves shown on the character sheet.
Meanwhile, the DM Log, although most of the pencil writing has been erased, it's still mostly legible.
On one occasion, the PC Firestone (NG Human Fighter 4) and his three NPC companions Striker (LN Human Fighter 1), Death (NE Human Fighter 1) and Hearty (NG Cleric 2) faced a number of opponents...
A Gnoll
Ogeres [sic]
10 orcs
Ratty the Lizardman
Teeth the Lizardman
Death the Lizardman, and
Strong the Orc
From that expedition, 150 GP was accrued.
Another expedition seems to indicate the PC was joined by a Manticore, Otyugh and a 8-headed Hydra, but I may be misinterpreting what the book was being used for by this point.
If you've bought second-hand D&D products, have you found similar legacies in the books?
Cheers!