Yes, hotels can ask for proof of service dogs in California. This requirement is based on the Americans with Disabilities Act (ADA), which allows businesses to ask for verification if the need for the service dog is not apparent. This proof can take the form of documentation, identification cards, or even a demonstration of the tasks the dog is trained to perform. Remember that hotels can only ask for proof if it is not obvious that the dog is a service animal. This is to prevent any potential abuse of the system. Service animals are protected by law and are allowed in public spaces, including hotels, regardless of any pet policies.