I leaned after attending Katsucon at the Gaylord Hotel that some attendees had done some damage to the hotel. There were pictures posted of a hole punched in a wall with tape placed over it saying ONE PUNCH MAN WAS HERE. Light fixtures torn down. Public restroom stalls covered with graffiti about the con. A hotel room flooded and someone urinating in a hallway. The hotel is a five star hotel and rooms are not cheap.
I have been to different cons and seen or heard of damage or pranks are done which will cause some con groups to charge more attendance fees to pay for the damage. I don't know if a lot of it is due to drinking or just being unruly while away from home. It doesn't make anime cons look good even most conventions, not just anime, have their problem people.