Yea, we actually have a little piece of paper up in our hardware store that explains that it's a 20,000 dollar fine for trying to pass of your regular dog as a service dog. Some people even try to pass off their therapy dog as a service dog, which doesn't really work.
As for my question, I have seen a number of people bring "service" dogs into the store. Some you can't pet, are very focused, etc. Pretty much what you'd expect a service dog to be. But then I've seen others that are running around sniffing anything, and the owners have no problem with you petting them. But they insist that they are service dogs. Are there really service dogs that are that unruly?
That's so great of your store! Most stores around me have signs saying service animals only but nothing past that; your store taking it a step further and adding what the legal repercussion would be is simply wonderful.
Unfortunately, a lot of people get service dog, therapy dogs, and ESAs confused, even though all it takes is a simple Google search to find out the differences.
Again unfortunately, some training programs don't fully train their dogs and will give them to their handlers half-trained. Alternatively, some handlers will get fully trained dogs but not keep up the necessary daily retraining/task work and their dogs training will deteriorate. Further, those could definitely be fakes. For the petting issue, I sometimes let people pet my dog, but under very certain circumstances. Some handlers have no issue with their dogs being pet whenever, others have a very strict no-touch rule, and others, such as myself, are somewhere in between.
Touching on the sniffing around thing: As a rule of thumb, if a "service dog" is sniffing around, I view it as a fake. One of the first things my dog and a few of my friends' service dogs were trained was to not sniff around.