I think Goo-Gone will get rid of sticker residue; I've used it on ponies before when they've had stickiness. You just apply the product, wait a few minutes, then wash it off with soap and water, if memory serves. I'm a little tentative to recommend it because I'm not sure if it could discolor certain ponies; always best to test first somewhere inconspicuous in case you get a possible discoloration spot. Hope that helps!