There were some beautifully recorded, mixed, mastered, and stamped vinly productions from the 60s on, and there were some poorly done also (ABCO for example).
Take a listen to Steely Dan's AJA from many decades ago. I'd match that LP against any produced today. There are many others that were also very well done..
If pretty much all your old vinyl sounds really bad, they probably are damaged.
Have any friends with good system that can play vinyl? Try some there...