Here's the quote as published in the Guitar World Magazine Special Collectors Issue of Guitar Legends, Issue #57 - Winter 2002:
The Doors were in NYC doing a TV show with (famed NYC deejay) Murray the K, and he brought us up to his office after the shoot and said 'Hey, I gotta play something for you . Ever heard of Jimi Hendrix?' Well, no...' So he put this record on, and I just couldn't believe it. People call the Doors psychedelic, but this was true psychedelic music. To me, Hendrix was the guy who was able to convey the feeling of the LSD experience in his music, whereas most of the people who took acid, like the Grateful Dead, played terribly. They may have been having fun, but nobody else got it
I stand corrected: He didn't rag on JA/Jorma specifically, I just assumed he did based on my recollection of his statement. My bad. Robby simply inferred that there were others that played terribly, but he specifically had the Dead in mind when he made his statement. I guess us DeadHeads out there don't count among those that didn't get it, LOL!