I see a lot of posts about “service dogs” and ESAs and general pets in Starbucks.
PETS AND ESAS ARE NOT ALLOWED.
SERVICE DOGS ARE.
We are allowed to ask two questions; whether the dog is a service dog and what tasks they are trained for aiding in a disability. You CANNOT ask about the disability (visible or not) and you CANNOT require the dog to wear a vest or be visibly identified as a service dog, ask them to perform a task, require the handler to present paperwork confirming the dog is a service animal OR about their disability (the list goes on and you can read more on the website I linked)
Generally, many service dogs will be wearing vests or be visibly identifiable as a service dog. But again, NOT REQUIRED. They are also not required to be on a leash ONLY IF the tasks they are trained for require the dog to be off leash (ex. getting help if the handler faints or has a medical spell, retrieving items, etc etc).
Please do not get yourself or your store into legal trouble for not following the law. You CAN legally ask those who are not in control of their dogs to leave, especially if they decide to treat a cafe floor as a restroom. Be assertive but try not to escalate the situation.
More info here : https://www.ada.gov/service_animals_2010.htm