Clear bra wrap is your friend.
The H is the second car I have had fully wrapped. While it is not a completely idiot proof solution, it does prevent some minor contact damage at shows.
I also roll the windows down partially. It allows people to check out the interior without having to put their hands on the door glass to see in. I do however, keep the window up high enough that the occasional idiot with their slurpee can’t spill into my interior.
When at a show, I always lock my doors. I do this for two reasons. The first is that the mirrors fold in, preventing accidental damage as people walk by. The second is that it eliminates some self entitled sack of dung from thinking they can open the door and “try the car on for size”.
While I am better about the H than my former SL, I am still VERY protective of my Countach.
I also have two personal car show modes, “nice D” and “not so nice D”.
Respect our cars, and I am a great guy. I will answer questions about the car, socialize and in many cases, unlock the door to let someone sit in the car. I will even take pictures of them in the car with their cel phones.
Disrespect my car, or any cars in our group, (as Ozzir, Nightlife or TTbear can attest) and I am a somewhat less than pleasant to the offending individual.