I must admit I didn’t see any foul play by the general public. However it might be worth having a sign reminding folk that many of these machines are privately owned.
Signs have been tried - no-one reads them...doesn't matter where they are, or what size they are.
As I've said in previous years - the vast majority of people without any understanding of etiquette are non-pinballers & a friendly word is nearly always enough - whether that be for not 'abusing' machines (
deliberately by slamming etc, or
accidentally by resting food/drinks on etc), or for having multiple games (either in a row, or putting 4-player on).
I know, as a teacher by trade, that I can diffuse most potentially aggressive situations through being courteous & friendly, but firm...and also at NLP I'm wearing a "crew" t-shirt...but, honestly, if you're ever at a show & someone's doing something you don't like...go &
speak to them in a friendly, non-patronising, non-aggressive manner - in 10+ years of going to shows, I've never yet had someone being aggressive, or unreasonable in response. At Daventry I've got to know a lot people by asking for a 2-player game when waiting for a game that someone re-starts after playing whilst I've been queuing, and at the NLP a lot are happy to be informed about stuff like multi-player games, or even 3-ball games, that they didn't know existed.
...and, yes, at NLP, a lot of people are ignorant to the fact these machines are privately owned & once they're aware they have a lot more respect - but seriously, the only way to overcome the ignorance is to speak to them...though we haven't tried having someone walk round with a sandwich board - volunteers for the next show welcome
Regards,
Dan.