It's funny, Grunge fashion is making a comeback. But it's updated and classier than it was before.
Back in the 90's grunge fashion was like anti-fashion, which became a movement in itself, just like punk became a movement of anti-establishment.
Today's "grunge" still features the classic flannel shirt, but today it's worn belted, over a nice shirt or tank top, and paired with skinny jeans or leggings, and nice shoes.