"Don't look" at the upholstery on this one! https://www.ebay.com/itm/1979-Mercury-Grand-Marquis-/302547853843?_trksid=p2141725.m3641.l6368
Yee-ikes! Squirrels nesting in the front seat? Dog searching for a buried bone? Got to be an explanation.
It can be simple damage over 15 years of driving; I don't think that's leather but leather can crack and key rings can damage a seat. On a related note, seeing this kind of condition shows why my grandfather used to put some kind of seat cover in his cars.
Drivers diet...... That is NOT leather ( been there, done that. use the t-shirt as a rag now, owned a 80 Colony with real leather....amongst other fords of the era with vinyl). the white stringy mesh what ever is vinyl. Ford did make a vinyl that when new would/could almost fool you, it was very durable yet once it got........ well the pics show it all............. Leather is torn. cut, etc, and that's it......does not leave man made fibers behind.....
The squirrel nest wagon is still available. https://www.ebay.com/itm/1979-Mercury-Grand-Marquis-/302653662927?_trksid=p2141725.m3641.l6368
I looked at a '85 GM CP back in 2012 that was in better shape than this one....and it was $1,000. I still said 'no'......