Dead. Where Is Thy Sting?

I blame entropy.

If you're talking about sound quality, the Grateful Dead, like Pink Floyd, put a heavy emphasis on superb sound at shows, starting with Owsley Stanley's ahead-of-their-time sound systems towards the beginning of their career. I've been to loads of GD shows since 1970, indoors and outdoors, and I've never heard a bad-sounding show.

If you're talking about performance, for sure sometimes the band weren't at their best - I've been to my share of those - but the best ones were magic and the sound crew was always spot on. 

With so many shows officially released You need not depend upon audience recollections or in fact, anyone else’s opinion.  You can hear for yourself and decide whether they are your cup of tea. Personally, I find them maddeningly inconsistent so I listen to the recordings I enjoy and don’t bother with the rest

While in the studio to record Terrapin Station, producer Keith Olsen cracked the whip and demanded they up their game. I don’t care for his production but their live shows in ’77 benefitted from his influence. This suggests they had the capacity to play at a consistently higher level but lacked the interest or drive to do so. This inevitably leads to a discussion of their so-called "ragged but right" ethos. I’ve already expressed my opinion of this in the past, so I won’t repeat it here. 

As to the "sting", for me it's out of tune vocals and at times, Garcia's wayward intonation. My ears/brain have a low tolerance for out of tune music.

I saw them years ago and Jerry Garcia would at times tell the group to STOP...and he would walk of stage ....lol.I think to much acid. Because your minds is telling you how to act.Like looking in the mirror and your taking to yourself  but there are two people, you and your reflection are totally different...lol.