In the 70's I used to use Ampex 406/7 tape for reel-reel recording concerts.
My friend likened the smell to his old army boots, unusual, but not unpleasant.
Suddenly new tapes we purchased smelled like puke, and we called them puke tapes thereafter, not knowing precious masters would later rot.
Turns out that was when the Great Oxide Binder Plaque (my words) struck the industry.
Years later the tapes would squeel and jam, and baking them would give a brief respite. The binder oozed through the oxide and stuck to the heads and guides.
My army boot tapes play to this day.