Kevin - I remember the scene changing over the years, especially after In the Dark was released. There was a time you could always fit one more person on the lawn at the Alpine Valley shows, then one day it sold out - I saw fights in the parking lot ... blah blah blah.
I saw the Dead all over the country, from the laid back shows with the older heads in Oakland and San Fran to the intense and exciting shows in the East where the crowd seemed wound a little tighter and rolled a little faster.
It seems that from around the mid-eighties on, the crowds kept growing, the vending and scalping got bigger and weirder, law enforcement seemed to be more high profile and the scene just became more uncomfortable. Of course, I got older and changed also, and maybe my perception of what's comfortable just changed. I'm sure that those who frequented Dead shows from the sixties and early seventies sensed even more profound changes in the experience.
I'm pretty sure that the bad crazies could be found around the Grateful Dead scene (or any band for that matter) at just about any time, but as their fan base grew so did the number of folks on a weird or rude trip. =)
On a positive note - I was expecting a trying time at the Vegoose music festival a couple months back, but the vibe was decidedly friendly and kind. Considering that the music ranged from Phil & Friends to Dave Matthews to Beck to Primus, etc. and the crowd ranged in age from very young to rather senior, I was more than a little surprised. It really took me back to my early Dead-concert-going days.
Tom