This is the first I have heard of this type of thing happening in the 5 years I have attended. IMO, its bound to happen at what point as the event grows. I think its best to just forget about it, theres really nothing you can do about it.
On a good note, I have seen the up most respect in the past years with people and cars. On several occasions I have had people ask me if it was ok to feel the paint, or if they could open the door to get a picture of the interior.
This year, I was approached by a young man in his early 20's who told me he accidentally brushed up against my mirror and moved it out of place (I have the old style mirrors on the door). I found that to be very respectful of him.