As the host, you can make it a house rule or condition that there in no eating or drinking on the beds or in the bedrooms. Put a statement in your listing. Tell your guests the house rules when you meet them in person for the first time.
I make it known to my guests that they are only allowed to eat in the kitchen or on the patio. This is out of respect for the next guest to occupy the room. Most guests will understand this so you should have no problem after the notice. If you do have a problem, you can file a claim for the damage and get some money back from the guest.
Also make sure you have a good water proof mattress cover and pillow protectors so spills, or anything else won't soak through. If you have a spill, the covers are machine washable. As a rule, I have at least 3 sets of clean sheets per bed to cover any situation. You can also raise your rates or cleaning fees to cover any extra costs.
Bottom line, as much as you want your guests to relax and enjoy their stay with you and get great reviews remember your house... your rules! You are still the Queen of the castle.