i've been to ACL ( Austin City Limits ) probably a dozen times by now. I would say it's pretty well run or at last as well run as a huge festival can be. There's always going to be people smoking weed or passed out in the bushes at large music festivals. I think the difference in a well run festival is well run utilities ( bathrooms and trash management ) and relief from bad weather like cooling tents, water bottle refill stations and things like that.

on the other hand, sometimes things just get out of control. A decade or two ago I was at lollapoloza (not very big) in Dallas at a large amphitheater and for some reason everyone started lightning these huge bonfires all over the place and it just went downhill from there. It just got totally out of control.