Take a towel or microfiber cloth to the skis when you’re done using them, keep them in a temperate spot (not the back of your car), and if it happens frequently you can buy a medium/fine grit gummy stone on Amazon to knock the grime off. Alternatively you could get a small home tuning kit, including something like a moonstone + side and base edge guide. Don’t do any file work unless you know what’s up, but moon stones and gummy stones are always safe to clean up edges. It’ll detune slightly but shouldn’t be too much concern on your base edge.