I hate that. As a matter of fact last summer I didn't wash my Z and left it dirty for a while because after I did wash it the previous time, they were saying 50% chance of rain every day for 3 weeks and it never rained... And of course I didn't drive the car to work since it was "really going to rain" this time and I didn't want my hard work messed up. No Z for 3 weeks? Screw that.
But at least it's not embarrassingly dirty. It looked like the guy took the car 4-wheeling when I got it back from having the tires rebalanced/aligned.