I'd just like to add to the discussion:
PLEASE, if you have time, consider returning your event tickets rather than using them as generics.
I run 20-40 player LARPs, with intricate plots. If my event sells out, but several people plan on not attending and don't return their tickets, other players are disincentivized to come to my game and try to get in--the event looks full, after all. Even when it's actually not, because someone with a ticket is planning on not attending. So I end up last minute having to cut plot lines or characters, which has a ripple effect on everyone else in the game. It's not very easy to write characters for the games we like to run that can be easily dropped.
That leaves an event that sold out actually in danger of not filling, which is happening more and more it seems. We had a good year this year, only one sold-out event not filling or over-filling once we accepted some generics. But I know many GMs, particularly those in the LARP community, face this difficulty. We try to encourage people to come with generics, but of course for some games, generic tickets to a sold out event are no guarantee. So some people don't bother.
So if you have the chance, please return your event tickets if you know you won't be going to a game in advance. Thanks from many GMs :)