Never try to wipe off bird crap...they eat dirt and gravel and it is deposited in their droppings. thus producing "bird crap sandpaper". The wet towel is a good idea, anything that will reduce the wiping will do fine. You can also try this..."clean the area of wax and dirt, then light clay bar, and then a little bit of "Nu Finish" (can be found at any auto store). This should restore the finish or at least make it less noticeable.