Glenfiddich 8 Year Old Unblended Scotch Whisky

I picked this jug up with a low-ball bid at auction.
I have no idea as to the provenance of it, and the cork quickly crumbled when I tried to extract it, necessitating a decant into another bottle.
I'm not even sure what era it emanates from - I can't seem to find any marker on the jug to point to this - but I'm guessing 70s or 80s?

Glenfiddich 8 Year Old Unblended Scotch Whisky (Ceramic Handle Decanter) 43%

Nose: Something sour at first, quickly turning to waaaay too over ripe fruit. Pureed apples. Something lactic and yoghurt-like. It's pretty out there. After a while some more recognisable notes appear underneath - some wood spice, a faint trace of honey. After even more time there's signs of integration as that near-rotten element dissipates, although hold on, now there's something plasticky lurking beneath. There may be traces of sweaty armpit and fish sauce there too, for good measure.

Palate: A fairly rich and full mouthfeel, considering the degrees Gay-Lussac stated on the jug. Ripe red apples. Over ripe oranges. Cumquats. A bit of spice. The fruit quickly becomes increasingly acrid and pungent. After 30 minutes or so things settle down a bit and we get a little more roundness. A touch more sweetness as the spice gains greater definition - cloves predominantly I reckon - while the (rapidly browning) red-skinned apples are joined by something red-fleshed like plum perhaps.

Finish: Medium long. A drop of plum sweetness initially, then increasingly pungent down the line. As time passes it takes on dried tea notes, all the while redolent of something vaguely sickly and milky. There seems to be a touch of smoke at the death too. Ashtrays.

Wow, pretty bizarre . But I kinda like it.
Old-school whisky. Old bottle ceramic handle decanter effect. Who-knows-what kind of storage conditions. All of that I guess.
The  initial nose is as close to rancid as you get without crossing that line, and while that fades over time, its feinty replacement is no less challenging. But after half an hour in the glass this becomes more "recognisable" and enjoyable to taste, while prior to that it is never anything short of interesting and bewildering to sip.