For me, it would be Silverchair. The first time I listened to them, I heard some of their new stuff, and thought it was absolutely horrible. As in, it made me want to stick hot pokers in my ears horrible, so I avoided them like the plague. Then I was listening to the radio and they were playing one of their older songs, and I was really surprised when I found out it was the same band. So i'll listen to their older stuff, but still avoid the newer stuff.