Gotta be done mate otherwise its like a builders clean which I dont have time to do, fair enough for those who want to. I did one years ago and never again, thankless job that was too.I have a couple of customers who recently had new fascias and soffits fitted and the fitters managed to get some sort of silicone or adhesive on the glass. I have told the customers I can't get it off and to speak to the fitters.