Artists that were hyped and subsequently well respected, but then became a huge joke a year or two later.
For an example, I suspect Justice fall into this category. I enjoyed Cross when it came out, but I can't even think about taking it seriously at this point. This is a tricky distinction. This category does not include artists that were hyped by the press and then suffered a huge critical backlash. This category leans more toward year-end list toppers that the test of time didn't treat very well, or that just fell the fuck off.