The word "Goth" covers a lot of ground and almost two millennia: from the marauding Germanic tribes of the second century, to pointy European cathedrals and haunting American literature, all the way to the "dark" fashion and music that still gets confused with devil worship.
The Gothic architecture that evolved in Europe between the 12th and 16th centuries--vaulted ceilings, gargoyles, pointed arches--did actually get its name from the Germanic tribes. Italian Renaissance writers apparently thought those cathedrals were ugly and chose to blame them on the barbarians who had done battle with the Roman Empire about a thousand years earlier.
But what better setting than a Gothic-style medieval castle for the dark, scary Gothic literature that developed much later, with the stories of Edgar Allan Poe, Mary Shelley's "Frankenstein" and "Dracula"?
Ghoulish encounters with vampires and other living dead gave the characters of Gothic literature a bad case of anti-social behavior--a stigma (or sign of prestige) that endures in modern Goth culture: moody, punk-inspired music, first presented by Siouxsie & The Banshees and Bauhaus, and the black-and-white death tones of Goth fashion.
One of the latest blows to the Goth reputation followed the Columbine High
School shootings in 1999; the killers were reported to have worn dark trench
coats and listened to angsty rocker Marilyn Manson. Wrongly perceived
as Goth, they were explained away as worshippers of evil--and members
of the Goth community weren't pleased.