I remember at one of the Les Enfoires shows I went to, to get a good seat, you had to get there around 9am for a show that started at 8pm. So everyone who got there early had a big bag with them to store sleeping bags, sweaters, blankets, etc because these shows are always in the winter.. I was with RMJ at the time and he showed me how he would bury his big expensive slr camera in the bottom of the bag. Back then, they didn't do a very thorough search and that's how he managed to get such great pictures over the years. I think the main thing they were looking for 'then' was Justin Bieber type water bottles.
At the first show I was at, I was up in the stands and looking down on the sea of people, you could see the red lights on the cameras people had that was a dead give away that they were recording and slowly but surely, you'd see those red lights disappear as security worked their way around.