Here's a few that I was a huge fan of, but recently lost interest for. This list doesn't include the many other artists and bands I have stopped listening to 2 years ago. XD
- All female pop artists like Ayu, Namie, Koda, Ami, hitomi, aiko, Shoko...
- All Hello! Project artists and bands (& sub-projects) like Morning Musume, Maki Goto...
- HIGH and MIGHTY COLOR since Maaki left...
My interest is MUCH more Korea-oriented now. After listening to so much Korean music, I started becoming turned-off by Japanese artists' voice.

There's just such a clear difference vocal-wise.