Yea, your perception of its legitimacy doesn't really have a legal leg to stand on. I don't see anywhere in the ADA guidelines where it allows to a store owner to refuse service if they perceive the animal to be fake. The ADA guidelines also allow for trainers, and all
dogs start somewhere. I'm not saying you are wrong or that particular scenario wasn't a fake dog, but I really hope you weigh the cost of those actions versus the benefit. I've already been involved with 2 parties who won lawsuits based on similiar stories.
The law regarding what is and is not a "disability" is pretty refined. You may diagnose yourself, but if it came down to a lawsuit, you would have to be objectively correct in your self diagnosis and what you diagnosed yourself with would have to be an actual disability.
From post 91
Service animal means any dog that is individually trained to do work or perform tasks for the benefit of an individual with a disability, including a physical, sensory, psychiatric, intellectual, or other mental disability.
People bring their pets in and call it a "service dog" does not make it a "service dog".
So, if someone brings their pet in, and calls it a "service dog" but it's not a "service dog" then no, he did not break the law.
The law covers "service dogs" not "pets".
Fake service dogs a growing problem - NBC News
Fake service dogs a growing problem
Under the Americans with Disabilities Act, it's a federal crime to use a fake dog. And about a fourth of all states have laws against service animal misrepresentation.
Often, people who want to take their pets into restaurants or retail stores just go online to buy vests, backpacks or ID cards with a "service animal" insignia.
Seems pretty defined to me.