alcohols like that turn up as unwanted byproducts in poorly produced/ cheap booze (especially stronger fortified wine; poorly distilled hard liquor or beer that has not been left in the Lager for sufficient time) – the Germans call it Fusel and this pub sign below (from some random place which is only just South of Denmark and where they use a dialect more influenced by Dutch) says that it makes you more dizzy/tired than good Bier.
That is true, I have been to DE in the early 2000s and you can literally drink some litres of it in the evening; have to get up for work at 07:00 (they like getting up early in Northern Europe) but not have a hangover.
