This thread reminds me of my last local convention experience.
The "Rpg organizer" of the Con approached me two weeks before the event, and requested that I run a few games. He had been given my name by a mutual acquaintance, and explained that they had very little gaming to offer and wanted to add more. He also requested that I allow the Con participants access to my large collection of pre-written adventures to "fill in the gaps". I reluctantly agreed, and set about putting together three seperate games for my slots. The compensation I was promised was a free pass to the Con.
I ran the games, provided prizes and certificates.
Upon completion of my final event, I decided to partake in some of the more social events (i.e. drinking and carousing). After a half hour of socializing, I was approached by a Con official, who asked to see my badge. He looked at it and announced that I would have to leave because the social events were for paid patrons only. My status as a "Volunteer" disqualified me from everything else. I decided to find the "RPG organizer", who when found said, "Sorry, them's the rules."
Needless to say, the only Con's I attend now are outside my home town.