I was delivering to the Braintree Mall and ran into the dog and guard outside, I asked him was the dog smelling for gun powder and he told me "certain gun oils/lubricants" he was not specific on which. Maybe he was lying.
The dogs are trained to sniff out gun oils.
If you have an ltc they will escort you out to your vehicle, You can then either leave your firearm In your car or leave the mall.
If you do not have an ltc the police will be brought in.