Nothing in reality......
Well the truth is there is no 'registry' for Service Dogs... Which indicates the registry for your Dog is much more than "dubious''
Id say they were well within their rights to refuse the Dog entry; therefore
The term Service Dogs takes in a huge cross section of Dogs also you see,
Dogs perform many services for different groups of people and individuals, They do in general have certification from the relative specialist organisation that trained them to perform that specific 'service' though...
Also what do you term to be 'Service Dog'? What service does it perform exactly....?
. For example a military I.E.D. Dog or attack Dog could be considered as a Service Dog.
As also can a mountain rescue Dog be considered a Service Dog
Just as Guide Dogs for the Blind are considered as Service Dogs... It's only the latter normally that is given the UNWRITTEN right of entry though
People who go around claiming they have service dogs are making life far harder for those who need and have real service dogs.... Our injured War vets for example, meanwhile have to suffer the consequences of their false claims,,,,,,,,,, Thats pretty screwed up in my eyes cos it's WRONG!