@Brian3620 ESA's are different than Service Animals and are often used interchangably with hosts and guests. ESA is an emotional support animal.
You cannot refuse to host a service animal if you are offering lodging to the public. The guest does not need to disclose the presence of a SA. Most will however whether real or fake.
Depending on where you are located, state specific, may have their own guidelines as to whether you would have to accept an ESA in public lodging.
If someone is telling you that they have a certified Service animal, they bought the certificate on line. Service animals are not certified, it would be nice if they were.
I would first clarify whether it's an ESA or SA.
There are two legal questions you can ask for a service animal.
Is the service animal required due to a disability?
What work or task is the animal trained to do?
Karen