I personally just chalk up damaged towels as a cost of doing business. Unfortunately, I've had a few damaged bath towels ruined because of makeup and now I leave smaller washclothes in the hopes they will use those instead.
Airbnb will ask you to ask the guests to pay. If they decline, escalate an aircover claim and depending on the size and severity, the payout can take a few days to a few weeks. Make sure you have receipts/evidence.