Sirius's father's old trousers

Sirius's father Orion owned a pair of old trousers that were kept at 12 Grimmauld Place after his death. In OOTP, Kreacher tried to save them from being thrown out by Sirius and the other members of the Order of the Phoenix and their family, but Sirius caught him "snogging" them and presumably threw them away.

But I thought that wizards were mostly unfamiliar with Muggle clothing? Was it possibly wizarding trousers? Or did J.K. Rowling become a bit inspired by movies?