I drank copious beer from the age of 14 to early 40s...
If I had beers that didn't taste 'quite right' it wasn't so easy to distinguish if it was an odd herby flavour variation, or just a bad conditioned pint...???
..and by the 8th round it didn't matter anyway..

Usually the beer could taste great going in, but then shortly after swallowing leave a hint of unpleasant after taste...
Perhaps something like burning tyre rubber...???

These days, when the wife is trying a new real ale in our local camra pub,
I'll sniff the top of her fresh half pint for old times sake.
and can still often detect after tones of something just a bit 'off'....