We can tell the difference in "new dust" and old dirt. Many shows have quite a breezy atmosphere and there is no way to keep all the dust off of a car. When the judge approaches your car, they will ask if you are ready to be judged, don't be afraid to ask questions or say that you are not ready. You will not be penalized, but try hard to be clean and ready by noon on Saturday, because the workload is very heavy at Grand Nationals. We all want to get the job done so we can all relax and enjoy the rest of the show.
New dust is blown in dust, leaves, twigs etc. and can easily be discerned from dirt or debris that is lodged in nooks and crannies. There is a great article coming out in the next Mustang Times about preparing yoour car for a carshow written by Jake Jarrell that you will want to read. Some very helpful hints.