Appalling recordings are numerous but how about "award winning" recordings that turn out to be really disappointing? Case in point: Robert Plant / Alison Krauss "Raising Sand" album of a few years ago? I bought this as I'm a HUGE fan of Alison Krauss and have certainly enjoyed most of Plant's production with LZ over the years past. I was shocked at the poor recording quality and not very impressed with the material itself. I think the accolades had more to do with both parties star status than with this effort. Compare the recording quality/arrangements on RS with any of Alison's last 6 or 7 albums which are simply stellar.
Worst record ever?
I had the misfortune of spotting Sarah Vaughan's "Songs of the Beatles" at my local record store and, intrigued, I bought it since it was only $2. I'm still traumatized a few hours after listening to it; who and why would ever release a record that bad? I love Sarah as a jazz singer but her rendition of the Beatles' songs is absolutely atrocious. I just can't believe someone made a decision to actually release it.