I know oil or grease will ruin the pads, not sure about melted plastic. Might be best to replace them to be safe.
Easy enough to figure out, sand down the surface of the pads, put them back in, do they work? If yes, recheck when riding in the rain. Rear pads can be changed by removing one bolt on my Wee. Otherwise they're dirt cheap if you want to buy new.
Current: '15 Tenere ES - 30k km
Past : '06 FZ6 - 115k km, '06 KTM 625 SMC - 30k km, '06 V-Strom 650 - 80k km, '07 FZ1 - 70k km
“Instant information is instantly obsolete. Only the most banal ideas can successfully cross great distances at the speed of light. And anything that travels very far very fast is scarcely worth transporting, especially the tourist.” - Ted Simon, Jupiter's Travels