THE most sonically dissappointing (lp) you own of great music?

I'll tell you what category of LP's are dynamically compressed.  Half-speed masters.  What a total rip-off they are.  When I was young and dumb (I am now old and dumb) I collected these things basically without listening to them, and when my rig improved, I learned just how bad they are.  Except for a few A&M half-speeds, I sold almost all of mine and bought the originals of the titles I wanted.  I also bought a lot of great new hardware with the proceeds.

Brian Ellis Group- Escondido Sessions. Suffers from home brew DIY production but damn! 

Agree with op on War on Drugs

i have yet to pick up an original but I do have an A&M half speed, "audiophile" series of Jobim's Wave that I may have listed as a letdown, it wasn't exactly cheap either, but that wouldn't be totally fair till I hear the original. 

I have 2
1) don Henley I can't stand still. Record was too bright no bottom end whatsoever.
2) mgmt oracular spectacular seems as sthlugh the music was compressed not good!

Adele - 19. Amazing songs and a great voice. "Mastering" could've been more accurately described as practicing.