I recently inherited my Dad’s 14 year old Cadillac sedan. The car is great-except it has a cassette deck!
Being a frugal type, I fond my boxes of home-recorded cassettes-and started playing them…I have a lot of jazz, and Pat Metheny stuff from the 1980’s…including a rare one of radio station KKGO (Los Angeles-when they were a jazz station).
Man, how weird it was? Some tapes were excellent-others had a lot of “wow”-one pre-recorded one simply broke.
Several others were bad-noisy and popping. I guess I’ll keep them till they break?
Question: will KKGO ever go back to jazz?
Digitize them now. Almost every computer has a line in jack, almost every cassette player has a line out or a headphone out jack. You can download Audacity for free – it’s a pretty good digital recorder – and convert the tapes to mp3 files. You can also do quite a bit of cleanup once you have some practice in how it works – get rid of a background hum or noise, change the speed of some passages, etc.
Yeah, save them while you can 
I used to make mixed tapes all the time growing up, including literally holding the tape player up to a radio and recording that way. I held on to them for a long time, and even just remembering them brings back a feeling, a smell, a sense of time and place. Quite awesome.
“Koo-loo-koo-koo koo-kooo-kooo-kooooooo!!”
How’s it goin’, eh…
A former resident of the house next door suspected his wife was having an affair, so he recorded all the phone calls. When he moved out about 15 years ago, he left a box of these tapes in the attic. The current resident found the tapes recently and is listening to them one by one. So far, no hard evidence, just boring mudane pointless conversations.