I highly doubt there will be a player clean up at Tippmann Challenge. It's a totally different event to the original game there, and aimed at different players as paying customers.
Clear paint still has a clear up requirement, though it doesnt leave the obvious coloured splats of not=rmal paint, and I expect used pyro to be required to be cleared, e.g. swept up. I'm sure this will be a staff clear up and time allocated after the event closes.
Call to duty was a very different event to the average scenario, and also had operational training taking place in Sennybridge after we left. I wasn't the last to leave, but there were convoys heading in as I was on the way out.
This exercise taking place meant that even if it were not under 'guerilla' terms there was no time for a post event staff clean up, without shortening the event itself, or requireing considerable manpower. This was made clear from the outset when the event was announced.
We were also camping inside the buildings (Not happening at T.C.) with the requirement to clear out each morning, with each faction being responsible for a zone, and building occupants responsible for their building.
A similar event in the respect of clearing up was the Reading Mall game, for this it was also stated that a player clear up was required. This didn't entirely happen and the organisers were onsite until pretty late. A few players left just after the event ended, others stayed a while for clearing up, I don't know how many stayed on until it was finished. (For various reasons this wasn't an entirely successful event so it was understandable for some to not want to hang around after paying to play and having the issues that occured)