Denim is a wicked material, the most notorious variety of it being light denim, and staining it seems to be the only possible way of incorporating any of it in a meaningful, aesthetically pleasing way in alternative fashion. This vest, I think, is a good, solid piece and looks excellent for layering, which is what Punk and its variations often favour. Indeed, layering is an easy way of enhancing the visual impact of an outfit, and when it comes to styles such as Punk or Deathrocker, the rules of mixing and matching are there mostly to be broken.
Nicely styled ensemble, too. See the back side of the vest here.