Been mulling over this for all of ten minutes now.
Off the top of my head I'd nominate -
Cromagnon - Orgasm
Wild Man Fischer - An Evening With Wild Man Fischer
Charles Manson - Lie (The Love and Terror Cult)
Throbbing Gristle - 20 Jazz Funk Greats (even if it is on the surface more of a user-friendly listen than its predecessors)
The Beach Boys - Smiley Smile (bearing in mind that it's possible to be quietly psychotic)
Tim Buckley - Starsailor
Chrome - Alien Soundtracks
Suicide - Attempted (Live at Max's Kansas City)
Jandek - Ready for the House
Big Black - Atomizer
Scraping Foetus off the Wheel - Nail