I am as OCD as the next guy when it comes to my car, but there are times that you have little choice but to valet. After all, it is just a car. If I took another one of my cars evey time I was less than 100% certain that I would be able to self park in a perfect space, I wouldn't get to drive the car much. It reminds me of my friend's dad when we were growing up. He splurged for the rear defroster in his new LTD, but would
never use it for fear that it had a limited life or would otherwise break!
When I need to valet, I always do 2 things. First, I am always very nice, friendly and respectful to the valet. They are doing a job and you expect them to do it professionally, so why treat them any other way? Second, I always tip them generouosly (but not obnoxiously) and always up front. I make a self deprecating joke about how protective I am about the car and ask them to keep it someplace where it will be very safe. At the end of the day, you are at their mercy. If they think you are a nice, generous person that can relate to them, they are far more likely to treat your car with the respect it deserves.