I agree with the sentiment that we should ALL treat our meet venues and whomever is staffing them with respect, pick up after ourselves, behave ourselves etc. We give our new team parents a handout regarding meet appropriate behaviour, and expect our families to represent us in a positive way at meets.
However, I disagree that parents working a meet are "volunteers". The host gym and/or booster club makes money from meets (sometimes a LOT of money), and the parents/athletes of the host club benefit from those monies made. So whether they pay you directly (I know they don't), or whether you are doing a work trade, you are getting a benefit from your sessions worked, whereas a volunteer is just giving and not receiving a benefit in trade.
When I write a check for $5000 and then know the thousands of extra that are coming from my families for gate fees, programs, snacks, goody-grams, raffles, etc. (from just ONE team)... I expect the trash to be emptied, the bathrooms clean and stocked, and the parents prepped beforehand on FAQ's: what time will the coaches food be here, are there any more water bottles, where is the wheelchair entrance, what time does the next session start, etc.
As a rule we would not attend a meet that charged entrance fees to spectators except in outside venues, which are worth the added cost IMO.