It is sealed
I have an early 1950’s bottle of Pinch. It is sealed, has never been opened and has been in a climate controlled home for as long as my dad had it. He got it some time in the early 70s from a friend that had owned a liquor store since the 1940s. I have a picture, but no skills to put the picture in.
That right there, is the key, and the one Number Six's father is missing.
Once bottled, spirits are not supposed to "age".Aging is done in the barrel. Well, at least that's the theory. Your dad bottle was open, so the alcohol has certainly evaporated. It does not look good, but how does it smell now?
Yeah don't drink that. Once enough alcohol evaporates it's no longer safe to enjoy. And it hasn't aged, at least not in the good way. I have a little collection going of rum minis, mostly 70s-80s. Oldest one I have is a 1940s Lemon Hart. There's partial evaporation, sadly, so it'll just have to stay on the shelf. My early 80s bottle of Lemon Hart is good to go though, suppose one day I'll open it.
Any alcohol I buy usually doesn't live long enough to 'age' in any shape or form lol.