toothpaste with a tooth brush you don't use and put a lot of tooth paste around the sole, i recommend white non flaky toothpaste and brush it hard and fast and when your done wipe it with a wet rag and dry it with a rag, if you got tooth paste on the fabric just soak them in hot water for 5 minutes and let them dry outside
If it's from age where the foam (or whatever material) gets yellow, as far as I know, there isn't much you can do. Some guys paint them, most just leave it. If they have an Icey sole and they're just yellow from wear, then cop Sea Glow and use as directed.
This is gonna sound nuts but I swear to you it works
1. Get a washing basin big enough to fit both shoes 2. Squirt a medium amount of toothpaste into it 3. Squirt 3 pumps of hand soap into it 4. Sprinkle a nice amount of shake 'n' vac into it 5. 6 sprays of Mr muscle (orange one) 6. Fill the basin with HOT water, stop once water level is above the outer sole. 7. Leave to soak for 15mins 8. Use toothbrush to get off stubborn stains 9. Use a cloth to wipe residue off 10. Use a towel to dry rubber
I shit you not this is a life hack, don't ask me how I found the concoction.. I'm weird like that.