@Daniel-Rusteen0 that sounds beyond annoying I must say . It also sounds like you have been had. It is my understanding that if a guest complains and it cannot be remedied by the host , then and only then could any type of refund be approved or the guest must also leave if they do not allow a remedy.One hair does not justify a refund ever.People are very weird about hair but that does not stop them leaving them all over your house. People shed , no one knows that better than an Airbnb host . I can only suggest that you do add a cleaning fee so if you lose it it wont hurt as much and also to begin taking a few snaps after cleaning and before guests. In future make them prove it. Always make sure under beds are vacummned and check for hairs that can cling even to clean sheets and blankets that you may have brought accidentally into the house. It all sounds very unfair ... Good Luck .. H