Nov 11, 2014 - 06:16 AM
Cobweb Cleanup can help, not sure if it will remove the stains. I am not sure if anything will remove stains that may be impregnated into the paint. Cobweb Cleanup will also help to repel new spiders and help prevent stains for a while. Reapply every 30 days for best results.
I would certainly test a small area first, see if the paint comes clean or if it comes loose from the siding. If primer was used before the paint, it should adhere fairly well. If not, be extremely careful.