not if you make sure it doesnt run onto the paintwork. before i got my colour code, thats what i used, kept the bumpers black and very shinny. Just spray it onto a old rag and rub it over your bumper. My mate uses used engine oil on his corsa b and his is always black.
Have just used MER Rain Away on my bumpers and door handles, worked a treat and comes off the paintwork easily. I know it can be expensive from car shops, but I bought mine from Boyes (can just see all you boy racers heading there) for half the usuall price.
used shoe polish to brighten my door handles, stips on side of the car, my washer jets and my boot lock surround that were faded quite badly, worked a treat, may need to add a few more coats tho as it isn't that dark and you can still see its a little faded.