Let's be clear here for people who don't read the links.
A service animal is not classified as a pet, period. Therefore it is illegal to refuse to rent to a person with a service or comfort animal (rare exceptions) Allergies in the home owner or future renters does not change the law. The disabled person's need for a service animal takes legal priority over your allergies. You may NOT charge a pet cleaning fee and the animal is not a pet. If there are actual damages, those are recoverable just as they would be if they were created by a human.
The law is linked above. Perhaps the reason a prospective renter may not disclose their service animal is that it would result in not getting the unit with some other reason given when it really was the issue of an animal.
https://portal.hud.gov/hudportal/doc...heo2013-01.pdf