I have stainless pipes, which present a different challenge than does chrome. Still, I've still had to deal with melted on nylon trouser legs, skin
and plastic bags whipped up off the road. Discoloration has been a particullar problem, so what I've done after using all the remedies mentioned is to spray the pipes with oven cleaner.
I first masked the side of the car behind the pipes with aluminum foil to protect the paint. I leave the cleaner on for 20 or so minutes, then wipe it off after putting on gloves to protect the pinkies. Darn if that stuff doesn't work, or so well it was hard for me to believe.