I deal with this mess all the time maintaining confrence rooms and such. I have found that typicaly the richer and higher profile the client, the more they trash a meeting room.
One of the worst ones was a fortune 100 company's executives who shall remain nameless came to use the chamber of commerce room here. I got a call from my contact at the C of C to come help him clean up and check out the system. They totally destroyed the confrence room! Two of the wireless hand-held microphones had dents in the tops of them where they had been dropped on the table. One of the lavalier microphone heads was dropped into a coffee cup, and didn't work period. They had written all over the video screens with dry-erase marker (which won't erase from a fresnel) They had their meeting catered, and were told specifically NOT to have food in the confrence room. The table tops have all sorts of stuff on them from laptop video connections, to boundary microphones, internet an d power etc. They had moved all the tables around and not bothered to disconnect the cables, so likewise, all the connectors were broken. The microphones had food spilled all in them, along with the carpeting and other stuff. They even had the nerve to leave the multimedia system running after they were finished, and the system stayed running, burning up hours on the projector lamps, all weekend long! It took another week of working on that place to get it back straight. They then had the gall to call up and ask for a discount on the room rental because the multimedia equipment was "Not fully operational"
On the flip side of this, I received a call last week from the rental agency where some friends and I rented a beach cottage. Before we left, we went over the house and did what I thought was a pretty routine cleaning. I got all our food out of the fridge, washed all the dishes & put them away, vacuumed up all the sand, made the beds, etc. Basically, put the place into the condition we found it, and a condition where the next visitors could walk right in. I thought we had left something untouched, or forgot to do or clean up something. Instead, they called to praise us on how well we cleaned up the house and that they have never had a renter leave the house in as good a shape. They said the maid didn't need to do a thing, and that they were refunding us all of the cleaning fee that we paid when we rented it!