I have a few boxes of old cassette tapes up in the attic, both home-made and commercial. A couple years ago I decided to digitize them. I still had a high quality deck up in the attic too, so I just plugged it into my audio interface.
Anyway, I was surprised by how terrible most of those tapes sounded. I didn't even bother with most of them. There were a few with sentimental value, like recordings of live concerts and my daughter when she was a kid so I saved those. Then there were about 3 or 4 that sounded really good for no obvious reason. I think print-through is a big problem with old tapes, where the signal from one part of the tape bleeds into the section wrapped around it on the reel. Also, I re-used the same tapes over and over and listened to them a lot, so that didn't help either.
If you want a real shock, take a look at your old videotapes - I have boxes of them too. Thought it would be cool to digitize some of them - until I watched a few. VHS quality just doesn't cut it today, I was shocked that we used to think these looked so good! Didn't waste my time digitizing any of those. 🙂